Added complexity versus added value
The core objection to Psionics in a Swords and Sorcery / Fantasy RPG (for those who do find it a problem) is rooted in two issues:
- Damage done to the suspension of disbelief due to genre overlap
- Additional mechanics with no added value
In my experience as both player and DM, it is the second factor that puts a burden on a DM in a psionic using campaign and tends to be the basis for resistance.
A detailed treatment of the root problems presented by The Angry GM match my own experience with attempts to fold psionics (a Sci Fi literary trope) into the Swords and Sorcery genre that originally inspired the game.
Experience as a grognard:
The introduction of psionic combat is bound to enliven games grown stagnant. It opens up untold possibilities for both the players and the DM, and in so doing recognizes one of the favorite topics of science fiction and fantasy writers: the unknown powers of the mind. ~ Tim Kask, Introduction, Eldritch Wizardry 23 April 1976
Despite Mr Kask's enthusiastic introduction, our early attempts to use psionics in D&D1 (Eldritch Wizardry Supplement in OD&D, 1976, TSR) exposed the problems of "psionics only encounters" and the clunkiness of the additional set of mechanics and rules. We didn't sweat the trope overlap at that table. At subsequent tables the "feel" factor arose with some frequency, but most DM's I played with in the first 10 years in the hobby didn't want to be bothered with the added complexity without added value. Angry GM points this out.
Remember, complexity is the currency with which you buy depth. Complexity isn’t inherently bad, but complexity that doesn’t add depth is bad. And psionics doesn’t really add any depth to the game in return for all the extra systems and classes and rules. When you combine that fact with the thematic mismatch, psionics rubs a lot of people the wrong way. {Aside: one could argue that it would be better said that "complexity is a coin with which you can buy depth," but that's prose criticism rather than answering this question}.
Some early structural problems
Psionics' generic problems were structural as far back as their origin (OD&D), which carried over into AD&D 1e as an optional rule set. (1e PHB p. 110-117).
It was acknowledged during 1st edition AD&D that psionics is different. An extended treatment in Dragon Magazine #78 was entitled -- Psionics is different ... And that's putting it rather mildly.
The difference was summarized as Magic being external to the character, and Psionics being internal to the character, but there was more to it than that. To illustrate the added complexity, Dragon 78's article had three pages of "Sage Advice" and over 20 FAQ's (before the Internet; Oct 1983). While original limitations on Monks and Druids were lifted (neither class were originally allowed psionics in OD&D Supp 3), the rarity of the talent and its "add on power" nature was a problem.
The complaint that only special (Mary Sue/Marty Stu) characters get psionics came from its accession. The player had to roll near to 00 (100%) on percentile dice in order to qualify. KISS was not the principle in question. With six players around a table, how often will one be able to roll 00, or roll just the right stats and then roll 90+ to 00? (No psionics for you!)
(1e PHB, p 110) Characters with one or more unmodified Intelligence, Wisdom or Charisma ability scores of 16 or higher might have psionic ability ... determined by a dice roll using percentile dice ... score of 00 (100%) indicates the ability exists. For each 1 point of Intelligence above 16 add 2% to the dice roll, for each 1 point of wisdom above 16 add 1% to the dice roll, and for each 1 point of charisma above 16 add 1/2 to the dice roll (drop all fractions). Example: A character has Intelligence of 17, Wisdom of 12, and Charisma of 17. There are 2 1/2 points to be added to the psionic potential roll because intelligence is 1 above 16, and 1/2 point for charisma above 16, total = +3 ... score of 97 or greater indicates psionic ability exists in the character.
"Clunky" from the get go, particularly when seen in hindsight after a few decades of effort devoted to cleaning up and improving on a host of things in the game.
Here ends the history. Later editions addressed some of the structural issues that came with the original package. By 3.5, and the Expanded Psionics Handbook, significant improvement was made (props to @KRyan for the analysis at the link).
Is the core objection justified?
At a given table, yes it can be, but in general, no it isn't, because neither of these problems is impossible to overcome. I've seen it done successfully.
- The first problem is mitigated by how a GM folds the system into the campaign. While this takes work up front, it can be done.
- One of the best ways to do that was by doing away with the separate encounter table for those "special" psionics encounters. All psionic encounters were planned / hand picked / timed / selected by the DM. (No random psionic encounters). Later editions' supplements improved psionics enough to reduce that problem.
- The second was best mitigated by a cooperative relationship between the player and the GM in getting the mechanics to play without delay or emphasis on how special this character is.
- Each PC is special in his/her own way: that's a core conceit of the adventuring party model around which the game is built.
When psionics got an overhaul in Second Edition, the authors admitted that it was not everyone's cup of tea2, and spelled out that these were optional rules: not core rules.
Bottom line
Psionics are only controversial if:
A "Session Zero" or "Same Page Tool" kind of conversation should sort that out before play begins.
That kind of conflict -- can I use this feature or not? -- was bound to arise in the bloatier editions (AD&D 2.0 and later) whose avalanche of supplements and features (What is core, anyway?) won't appeal to every DM.
It is fair to say that psionics isn't alone in being a table-by-table feature in the game.
- Example: In our current campaign (5e) the DM did not approve Variant Human for our table.
Since DM's don't DM for the pay, that isn't a bad thing: it's either available at a DM's table, or it isn't. No controversy.
1 Psionics was initially added as a feature in a monster before it was
available to PC's in Eldritch Wizardry. The Mind Flayer showed up first in Strategic Review (Issue #1, page 2) with a power that formed the core of later psionic attacks: Mind Blast. Over a year later that psionics arrived in supplement III.
-
From this web interview, we find that Kask and Gygax did not like
psionics with equal vigor Tim Kask:
I LOVED psionic combat and had great fun devising it with all of its
tables and charts. Apparently I was in the tiny minority. I guess
mental combat was too esoteric for most D&Ders; not enough of them
shared my fondness for the Dr. Strange Marvel comics and Mindflayers.
God, I loved Mindflayers; they were all over my dungeons. I just loved
the idea of turning an annoying PC into a gibbering idiot.. Oh well,
live and learn...)
Gary Gygax:
As for the psionics, that can of worms was my doing. I had created the
mind flayer as a fine monster, and I should have left well enough
alone; but no! I had to add mental powers, send the initial draft
around. I soon hated the whole business, but Len Lakofka and his group
in Chicago loved the concept, and Tim was enthused about the addition
as well. So, as said Pilate, I washed my hands of the matter."
2 From the Second Edition p. 1-3, Complete Psionics Handbook:
Psionics was not included in the AD&D 2nd Edition game. Now psionics
is back by popular demand ... completely optional addition to the AD&D 2nd Edition rules.
So it is not unreasonable to ask, "Does the game need a third type of
magic?" The answer is no, the game probably does not need a third kind
of magic. But the question is misinformed because psionics is not
magic. Magic is the ability to shape, control, harness, and utilize
natural forces that infuse the game world and surround the characters.
The key element ... is external energy. The power does not come from inside the wizard or priest but from somewhere else. Psionics is the complete opposite of this. The psionicist shapes, controls, harnesses, and utilizes natural > forces that infuse his own being ... more than a character of any other class, the psionicist is self-contained.