I wouldn't go so far as to say "useless", but I believe I understand the sentiment. Back then (meaning in original BG games) you play a rogue because 1) lockpicking, 2) trap disarming, 3) pickpocketing, 4) stealth - good as a scouting and escape tool, 5) backstab damage, and 6) "use anything" (or use scrolls if game is modded) high-level ability.
Based on my experience playing Pathfinder:Kingmaker (~80h so far, Knife Master Rogue), now you play rogue because 1) sneak attack damage, and 2) more skill points, so you are good at more skills than other characters. It's not bad, but rogue definitely feels less distinctive. Other classes can also be a skill monkey if they have high INT. Bards can pick locks + disarm traps too. And disappointingly there's no pickpocketing in this game. Basically, most of the things a rogue can do can be done by other classes, it's just that a rogue is good at more things at the same time than most other classes. Now if the only thing you got going for rogues is "sneak attack deals plenty of damage", that's pretty weak tbh. Their high damage per hit is just a benefit they get in exchange for the drawbacks of being a rogue.
Except for disarming traps, you could substitute the rogue with other classes in the original BG too: rangers could stealth (and in BG2 stalkers could backstab), locks could be bashed with high strength or the knock spell, bards could pickpocket (and also got use any item in BG2). There was also a spell to detect traps, though it would not disarm them.
In PK I'd say having a main character who has lots of skill points is worth it, because in some instances you cannot use your party to make the roll, and skill check yield (at least when I've played) lots of experience.
