Personally, I think the engineering of weapons purely on DPS increase is a bad idea. I like the idea of modding weapons for larger mag size, recoil pattern and optic magnification, etc and hope they get that part right. As far as FPS go, I like the Planetside 2 approach to weapon mods.
As long as the option to upgrade your weapon damage is in the game, you're putting yourself and your team at a major disadvantage by not utilizing it for PvP and "high-end" PvE. The problem, as it's been discussed many times in this thread and others, is that the process of engineering those weapons is not particularly hard or difficult, it's boring and RNG-based frustration-inducing tedium.