I mean, Rogues in tabletop have the same problem. When anyone can be a sneaky trapsmith (half-elf Artificers are especially guilty of this), what's left for the rogue?
Fact is, Rogues in 5e are not the Thieves of older editions. They're a martial skirmish class like the Barbarian. The biggest nerf to Rogues in BG3 is that Ranged Legerdemain can't pick locks or disarm traps. Thief rogues get a whole extra bonus action, which is insane. They get to disengage or dash, sneak attack and stab someone with their offhand weapon. Because of how TWF is implemented, they can even do a dagger stab, disengage, and then use ranged sneak attack with a longbow (what do you mean you're not an elf?).
Remember. 5th edition is 4th edition dressed up as 2nd edition. 4th edition was designed to appeal to the WoW/GuildWars crowd. Even though we have Proficiencies, abilities that recharge on rest and the traditional core classes, it's still very much built around the combat round, cooldown abilities and special equips.
