Ok. We'll see about that...
How many truly empty rooms have you ever been in? The only time a room is truly empty is when it has been throughly cleaned by someone with the deliberate intent of making it empty. In all other cases, empty rooms are unrealistic.
Now, you probably think that there is some difference between a generic room and an empty room, but I don't. A room which has been given a generic description is like a room wearing the emporer's new clothes. You may think its not naked, but the minute the PC's actually look at the room, either a) you are going to have to actually spontaneously dress it, in which case the generic description didn't do you alot of good, or b) they are going to realize that the room is unimportant because you didn't or can't bother to think of actual details.
I don't see how you figure that. Empty rooms to me are like dragons in 10'x10' rooms. Surely someone built that room for some purpose. What was it? What evidence remains of that former usage? What's it used for now? Does any nearby inhabitant visit? What signs of thier visitation did they leave behind (tracks, spoor, litter). If not, what is it about the room that keeps people way? Ultimately, alot of generic rooms puts the characters in a maze problem in which each particular element of the maze is by itself rather uninteresting. Maze problems use to be my absolute favorite dungeon elements when I first started DMing, but gradually I began to realize that what looked cool on paper was usually tedious to play through. Today, I'd rather make the various locations of the maze interesting (so that being 'lost' is sorta fun...at least for the players), or else skip the maze entirely either by removing it from the design (in a location based adventure) or handwaving it (in an event based adventure).
Time which you could spend on describing something more important or developing more interesting locations, challenges, puzzles, clues, etc.
You can't interact with a generic room. To interact with it, it has to become non-generic - which was precisely my point. A list of descriptions is interesting to a DM only in so far as it fires up ones imagination.
Not really. A truly detailed location is always complex enough that the player's generally don't know whether they are missing things, and generally speaking in my experience are missing things. A raw description of a room isn't really details. It just provides a jumping off point for providing details. If you aren't willing or able to add those details, I'll quickly be able to tell as a player that the room/item serves no purpose in the dungeon even if my character can't.
No, a dungeon which only contains what is important is like a work by JRR Tolkein. A dungeon which contains all sorts of unimportant but highly detailed things is like a work by Robert Jordan. A dungeon which contains a bunch of tacked on empty rooms is like a novel that doesn't get published because the editor finds it boring and unprofessional.
But, analogies obscure the truth, so let's just avoid them. The really important and interesting part of that sentense is the word 'say'. It indicates that you don't really understand what I'm talking about. What I'm advising has nothing to do with the verb 'say'. I'm not giving advice on how to
run a dungeon. I'm giving advice on how to
design a dungeon. My advice is that if you can't think of interesting things to put into the room for the PC's to play with, don't put it in the dungeon. I'm not saying that you should only have descriptions for important rooms. I'm saying that you should not have uninteresting rooms at all. If you don't have uninteresting rooms, then you don't need descriptions for them. If you have uninteresting rooms, giving them interesting descriptions is a waste of time, because it won't be long before the PC's realize that the description is just a 2D description, and has added no more to the room than if it were painted on to the walls.