For some context, I am playing level 20 Barbarian, with 24 STR and CON, and have mostly adopted the totem of the bear.
When we began our campaign many levels ago, my role was to force enemies to target me, while also dealing lots of damage. I was also responsible for most out-of-combat scenarios involving strength, or other classical Barbarian roles (eg scale that wall, intimidate that person, etc). Realizing this, I spent all of my ability score increases in STR and CON, spent my gold on damage dealing items (like a Sword of Sharpness), and took feats to support this role (Shield Master to avoid damage on successful DEX saves, and Sentinel to force opponents to target me).
However, now that we have gotten to level 20, I worry that my role in the party is becoming eclipsed by other characters.
For example, the rogue in our party recently acquired a belt of Fire Giant Strength, upping his strength score to 25 without having to spend ability points like I did. While certainly good for his character, I worry that this single item makes my character's strength obsolete, since it was typically my character who was the king of strength. This is frustrating given the amount of work it required to get myself to such a high STR. Now, when scaling a wall to invade a castle for example, our Rogue is suddenly the better fit, since he now not only possess the strength to scale the wall easily, but also has the stealth skills that would allow him to be better suited to these trespassing-esque tasks. With sneak attack he is also able to deal huge amounts of damage in combat, again encroaching on my historical role as the main damage dealer.
Similarly, our party's Bard has become a skill monkey, meaning that my intimidate is no longer the best in the party, even though I am a Half-orc Barbarian and he is a Gnome.
While I recognize that we are all a team trying to survive the campaign together, I am worrying that my role in the party is slowly being absorbed by other party members.
Please don't misundertand: these concerns are not coming from a place of jealousy or frustration, but more from a concern that my enjoyment and involvement in the game is going to be minimized since I will no longer be the go-to person for many tasks I used to excel at. However, some frustration does admittedly come from the fact that I have now burned ability score increases, taken feats, and built my character in a way that, in a level or two, feels to have been almost entirely eclipsed by other characters.
As of now, I feel like my role has been reduced to taking as much damage as possible in combat, while other players do most of the heavy lifting. This usually involves just me standing next to enemies and hitting them, which gets pretty boring after a while, especially when my character is no longer the heroic barbarian of our party that he used to be. While I understand this is still a role to be played, it feels shallow, and not particularly meaningful given the much more varied roles the other PCs are now playing in our party.
So how should I deal with these changes in our game, and in my role in particular? Am I being oversensitive? Are these changes just a part of the game that I will have to deal with? Or have I just made poor decisions in optimizing my character to this point, in choosing to venture deeply into certain areas (STR and CON) instead of diversifying like my fellow PCs? Should I be speaking to my DM about this (though I'm not sure what he can do)?