And I'll say it again, just because if might work in one game doesn't mean it will work in another game with another game engine. Unless you are a programmer and have used the engine they are using you can't say for certain that it will work. This same thing was asked for in Morrowind and in Oblivion. I'm sure every time they make a TES game they try and make this work.
It's not a big deal really.
Well, speaking as a (at least attempting) programmer, your engine does what you want your [censored] engine to do. They're built, not born, you decide what you want and then you make it happen, you don't take what you're given and work with that.
If bethesda decided, as a purely objective choice, to implement some form of seeing through windows, whether it be dynamic loading of interiors when necessary or a deferred rendering like portals, then it is in. If they decided against it, because they didn't want it, not because they didn't think it could be done (because it can, and they're capable), then it is not in.