Quess that was also a bit cause of technical limitations.
I think more of it was due to bad ideas/designs which were given more traction than they deserved. It's the same reason Thief has several awesome raid-the-mansion levels mixed with some very subpar run-around-caves-and-fight-zombies levels. There was just nobody around to tell the designers, "no, this is a really bad idea and you either A) need to make more good levels or B) just stop making levels completely".
Blood actually uses an advanced version of the Duke Nukem Build raycaster Engine.
Build is not a raycaster, it's a portal based engine kinda like Unreal.
That game was actually made very recently. It's a homebrew project and "MOOD" is just "DOOM" backwards. Take a look:
http://csdb.dk/release/?id=40255So it's not legit "old-style" and I don't feel bad to call it ugly as fuck either. No c64 developer from the '80s would've made a 3D game on the system knowing that it would look that bad.