Just going to say that making things intuitive and fluid is part of a good design. Someone could argue that something is poorly designed if it's counter intuitive and he'd be a 100% right. If something is so counter intuitive that players still get confused after repeated mistakes, you know you have to rethink your design. It's perfectly reasonable for players to expect being able to go in this door since the exit sign was specifically designed to direct players. That's right, the current level design directs the player in that door. Also, this door model is usually animated. If doors made with this model open in maps like cp_steel and and cp_well, how can the player know it won't open on your map. Expecting the door to open seems perfectly reasonable to me in every scenarios. So reasonable in fact, that if I found out ingame that the door didn't open, I would assume straight away that the door was broken for some reasons and I'd try it again later to see if it the door worked. I get what you're saying about detailing and nostalgia but the point remains that everything about this is counter intuitive. if you really want to keep this door, you should at least account for the counter intuitiveness and add a sign that says "closed" or something. Now that would be functional detailing.
There's just no excuses for me and you can't just dismiss issues pointed by yyler as they were all valid in my opinion.