that's how Wolf3d, Doom and Doom2 worked... it's the formula!!
The problem was that in RTCW, the levels looked decently realistic. It wasn't a sliding wall revealing a secret chamber. It was literally a zombie smashing its way through bricks, leaving a jagged brick hole behind it, and showing that it had been well and truly walled-in up until the moment that I walked by.
The more believable your graphics and architecture become, the more the gamer starts to judge it according to their understanding of real places.
Funnily enough, I would have been more accepting if the zombies were appearing out of thin air via some kind of teleportation device. As a gamer, I can pretend that teleportation exists in the game world, and that something is using it to try to put a stop to my character. The idea that traps have been set by physically sealing zombies into brick walls to wait for me, OTOH... that's just dumb.
Yeah, it's just a game and I'm over-analysing it -- but this was basically my reaction at the time I played it.