I know that if you turn them off that the game looks like ****. I mean that instead of using bumpmapping they should use more detailed textures because the textures in Doom 3 are ugly as hell (from up-close).
for the game i dont know but as for the details (normal map) (bump map) yes doom3 models were about 1.5 million average, and for uake4 they are using 4 million polys, so thats why the models look realy more smooth, and well i think they also raised the poly count a little bit.
up close all texture in all games are bad. In fact, HL2 and far cry are just as bad if not worse than d3 is this area, HL2 is the worst up close actually.