i kinda disagree about multiplayer. i mean there are still people out there who make and play doom maps. and sometimes im like, i feel like a game of doom, clear 3 maps and i put it away for another year.
before q3a came out fps games had everything. good multi, good sp. look at how badass quake2's game modes were. you could do sp, coop, dm, ctf, whatever. after q3a/ut came out games were either made for multiplayer or singleplayer exclusively. sp games went story driven (and eventually sandbox) and mp games went for multi arena and class based team play multi. so the fps genre has a been fractured into a ****ton of subgenres.
Well, in a way that's the Bethesda effect, they saw the FPS engines, and realised that, with work, an engine like that would provide an entirely new way of presenting Role Playing Games that fulfilled the fantasies of every D&D player out there. Now you could not simply watch your character, you could be
The interesting part is that the whole divergence of types is actually starting to blend back into itself, where we now get games like Fallout or Borderlands which, whilst wearing a 'Sandbox RPG' mask, are really Sandbox FPS games in my opinion. I'll note here that it's perfectly possible for a FPS to have an excellent storyline, this is not an observation on that so much as an opinion that Role Playing is not the same as 'Level Grinding', a fact that does not always survive the transfer to computer very well.
I think ID were perfectly aware of the multiplay potential of Doom when they created it, but technology got in the way, the only real way for most people to play was by Serial lead, which was a pain. In many ways, despite the fact that Multiplay was difficult, it was the multiplay that helped keep it alive far longer than, say Blakestone or even Wolfenstein which didn't have the ability iirc.
It's difficult because there are exceptions to the rule, the Elder Scrolls series were all about level grinding, but when they tried to create a system to mitigate that effect, it didn't go down too well, Borderlands have stories that are part of a larger plot, which suggests roleplaying elements, but all wrapped up in an arcade-style shooter etc.