All DnD games have problems with level cap, the reason why Fallout 2 or Jrpgs didn't have this issue, is because their systems were different. In majority of JRPGs, the only thing lvlups add are some numbers, so you can completely ignore lvl cap, let people lvl up endlessly, no fucking problem. Fallout had some perks gated behind levels, highest are at lvl 24, but they can still let you levelup for a looooong time after that, with no more unlocks but letting you pick previously unlocked ones, there is no class and shit to limit you, you can let player grind random encounters for 500 hours and get all the perks in the game if he wants.
DnD and similar systems, on the other hand, have class-specific leveling, and nearly every level is supposed to unlock some class specific stuff. New spells, abilities and shit. You have to pick a level cap, and you have to pick one that majority of players will reach some time before the ending of the game, because every new level you offer players requires shitload of dev work, and you don't want people to finish the game unleveled and miss out on that. Average casual will usually skip a lot of side quests, so devs tend to make level cap very easily reachable, which unfortunately also means that completionist players will reach it far too fast.
I always thought the problem was in devs trying to stick too much to the DnD and also blindly following the way games like BG2 did it, ignoring the fact that this shit doesn't really work well in a video game format. Devs could easily add some retarded "prestige levels" or some shit like that, which would be achievable after reaching level cap, and could give you ability to pick more of the stuff you had available on lower levels, or give some abilities from other classes etc., which wouldn't require much dev work, but would make things more satisfying for completionist players - pretty much what Fallout 2 does. If extra levels make content too easy, then simply add some harder difficulty modes to choose, slap +50% stats on enemies, call it "unfair" and your work is done, everyone's happy.