Because it was like a very bad survival horror game that only did the themes and atmosphere well and sucked balls as a FPS for the most part.
Please explain how mechanically it is a bad "survival horror" my friend, because I don't agree. I would go as far to say you are wrong as fuck on the matter.
the flashlight concept (keeping the mods out of discussion) was a very artificial way to add tension/intensity to the gameplay. the lighting is truly dumb too - areas where there are clearly lights in the ceiling or on the walls that are bright, but surround areas that are dark for some reason.
this. in terms of mechanics (even though the graphics/atmosphere said otherwise) the game felt very cheap. hell, even heather from sh3 (released a year before doom 3) can figure out how to use a flash light and a gun at the same time. okay, so you fix the shitty mechanics with the duct tape mod...
well... after a few hours you didn't grow tired/bored of the same predictable jump scares? It was as bad as DS2 in that aspect.