Low-level wizards measure up fine because
Low-level Combats Are Incredibly Lethal
In a group of brand new, fresh-from-the-core-rules group of PCs, the wizard--with his bad Armor Class, bad weapon proficiencies, low hp, middlin' class features, and 2 or 3 spells per day--will appear to be unable to measure up to the killin'-all-the-time fighter or the I've-spells-and-armor-and-weapons-and-channeling cleric.
But, then, look at this orc. He has AC 13 and 6 hp, but he's attacking at +5 to hit for 2d4+4. His ferocity extraordinary ability gives him sort of, like, 10 extra hp, and that falchion--with its wide threat range--makes a lot of level 1 characters just dead.
There're 3 of those orcs in an EL 1 encounter.
And you can expect 4 encounters each day.
There's a lot of adventurer blood on those falchions, and it's not all wizard blood... although it may feel that way sometimes.
Beginning Wizards Use Crossbows
Most folks who sign up to play wizards think they're going to get to play Raistlin, Gandalf, Harry Potter, or whoever, but then, after winning the the day's first and second encounters via the spells color spray or sleep, those folks are out of spells and stuck with their light crossbows.
You know what that makes them? Crossbowmen. A beginning wizard without spells should act like an archer because he is. An archer stays in the back. An archer delays and readies until he's got a clear shot. An archer lets his party know if someone needs to move. An archer moves if he can't get a clear shot. An archer spends some of his treasure on archery stuff--masterwork bolts just aren't that expensive, and a dozen is probably enough. An archer uses cover. A crossbowman can even drop prone to avoid enemy missile fire and keep firing. Seriously, a beginning wizard can apply his arcane bond class feature to a light crossbow and just start with a masterwork one:
Wizards who select a bonded object begin play with one at no cost. Objects that are the subject of an arcane bond must fall into one of the following categories: amulet, ring, staff, wand, or weapon. These objects are always masterwork quality.
Such a wizard will take crap from theoretical optimizers, but, y'know, it doesn't matter how awesome a character would've been if he's dead.
Low-level combats are supposed to teach everybody how combat--mundane and magical--will be run with that DM in that campaign, and all players and characters need to be on the same page for when they engage in bigger combats with nastier threats later.
A starting wizard has an average of 70 gp. Here's a shopping list:
- crossbow, light (35 gp; 4 lbs.)
- bolts, crossbow (20) (2 gp; 2 lbs.)
- club (3 lbs.; 0 gp), dagger (1 lbs.; 2 gp), and/or quarterstaff (0 gp; 4 lbs.)
- leather armor (10 gp; 15 lbs.)
- spell component pouch (5 gp; 2 lbs.)
- sacks (6) (6 sp; 3 lbs.) for loot
Rolling well on starting wealth adds to this list the following:
- scroll of cure light wounds (1st-level spell at caster level 1) (25 gp; 0 lbs.) given to a PC who can use it
With this load, the starting wizard casts his 2-4 spells then dons leather armor and becomes a crossbowman. The wizard should sleep in his leather armor, too, if he's cast all his spells for the day anyway.
It's understandable that most wizards don't want to be crossbowmen. Here're some ways out of that bind.
Patient Wizards Contribute More and Live Longer
Having a beginning wizard in the party is a burden. He needs his beauty sleep to prepare spells. He's got a really wide but very shallow power meter. After one or maybe two encounters the wizard should encourage the party to knock off for the day, reminding the party that--despite their impatience--it's better to have their wizard at full power than have just another crossbowman.
Encourage the DM to Start the Campaign at a Level Greater than 1
This might be the real problem. Some DMs never get the idea that campaigns can start at any level the DM wants. Really, there are very, very few pieces of media that simulate a character's growth from Wizard Who Casts Sleep Once Per Day to Wizard Who Casts Wish Thrice Per Day, and, really, most folks want to play something in between anyway. Talk to the DM. See if the DM'd be willing to start a campaign at level 3 or 6 or 10 or whatever instead of always 1. Or start such a campaign yourself--then your bad guys can cast at the PCs the awesome spells you've always wanted your characters to cast (and now those are your characters!), and when those bad guys are defeated, you get to try different bad guys with different spells versus the PCs.