FPV RT combat and RPGs just don't work together. Every single game that has tried it has ended up with clunky, medicore at best combat.
The first two Gothic games had pretty good real time combat (melee). They were third person, but the same system would've worked in first person.
It's true that most First Person RPGs do have shitty combat, but as someone mentioned already, that's also true of most RPG combat in general. Theoretically, there is nothing preventing developers from coming up with a good RPG FPP real time combat system. There are however a few common obstacles to this. The first is that real time combat must be both timing and skill based (player skill), and most RPG devs are scared to death of making such a system because it might be disliked by both casuals looking for easy games, and by some hardcore nerds who cannot handle gameplay requiring reflexes/coordination at all. This is why cool gameplay mechanics like a timing based parry in Gothic games gets turned into a pointless "hold parry" mechanic which the enemy for some reason hits into anyway in Oblivion.
Another common obstacle is the RPG devs insistence on thinking about real time combat in terms of numbers. This is a hold-over from tactical RPG combat, where numbers play a big role, but in real time combat, having numbers related to hitpoints, damage, weapons and so on change throughout the game as you level up just really messes with balance and the mechanics. What they should do instead, in my opinion, is have the player gain new abilities, for example, that they can use in combat, while their numbers stay the same. Enemies would also have various collections of those abilities depending on their target difficulty, and then the combat system could be designed around the overall set of those.
Finally, good real time combat requires a heavy investment. There are basically entire genres built around good real time combat (e.g. FPS). RPG devs have a lot of other costs, writing, quests, world design, etc, so I am guessing SS2, DX, and Fallout 3 did not have nearly enough spending on their shooting mechanics as a typical FPS.
