[…] i wonder why only DooM 3 gets flack for its monster hiding in closet enemy design...
Doom I & II and Quake have a very different attitude than Doom 3 when it comes to level design (and other things). Earlier id levels do not pretend to be more than just challenges you need to beat to reach the next one, so the military bases, fortresses, temples, labs, power stations, or cities, do not feel at all like the thing they are supposed to be. And since they do not try to make you think otherwise from the very start, there is no reason to see them that way. In that context it is hardly jarring to have a wall open behind you and unleash monsters when you pick up a piece of armour—Serious Sam did something similar by teleporting waves of monsters when you pick up some bonus. Doom got very creative with stuff like that, often going beyond the "closet" scope and ending up changing the layout of a level by picking up stuff or pushing buttons, usually unleashing monsters in the process. It simply fit the action gameplay based on mobility.
Doom 3 on the other hand tries to have realistic environments, which is something the earlier versions of Doom tried to do and that was then scraped because apparently having more realistic levels did not end up to be fun. It's something you can already see a bit in Quake 2, where the environments are still based on the action gameplay but try to make more sense from a realistic point of view, so you still get monster closets but nothing that radically alter the level. It doesn't offend in Quake 2 but since Doom 3 tries to be believable, the fact that most walls open behind your back or your sides to unleash monsters feels out of place and doesn't make sense from the perspective of a real place. But much worse than making sense or not, that kind of thing does little for the gameplay. At much getting ambushed by a couple of monsters at a time is a mere annoyance and that's it. Again in Doom, and in a certain measure in Quake 1, moving walls and changing levels is a defining feature of the gameplay and a reason why people still make maps for these games today—and they got tougher with time!
Unlike apparently many, I never got a problem with Doom 3 trying to do something different than its predecessors, but my issue with it is that it was kind of half-hearted when it came to the gameplay, trying to be a bit of a throwback to the old style while appealing to modern sensibilities but not succeeding at any of these. It's still a good game, with great visuals and sound and decent action, but that's what it is: good, not great. Coming from the guys who basically defined the genre with Doom, which is still in a category of its own, and Quake 1, that's a bit disapointing.
For me there was absolutely no comparison between Q1 and Q2 soundtracks. I switched Q2's obnoxious compressed guitar pseudo-industrial metal almost instantaneously, whereas Q1's ambient soundtrack lingered with me for a very long time.
I initially disliked the Quake 2 soundtrack but it grew on me over time. It's more suited for the action gameplay of Quake 2 that is more about dealing with the enemies than the level itself like Doom or Quake 1, but in turn it doesn't feel as unique as the Quake soundtrack. It's ok for that purpose but is certainly less haunting. Reminds me of the soundtrack for Painkiller, which does the same by accompanying the action but being pretty forgettable outside of the game.
Main theme isn't really representative of the soundtrack as whole, though, the rest is... well, maybe not "calmer" (because 'calm' doesn't really fit anything quake), but more subdued and moody - perfect sound backdrop for those dark corridors.
The track goes more in line with the rest of the soundtrack after the initial minute. Still, that part sounds great and fitting for when it is played, mainly for when the game is started and when you complete an episode. It has a nice gritty and foreboding sound to it for these few occasions.