As a PC gamer, mods are one of the top reasons I do use PC. When it comes to Skyrim for example, I consider myself extremely involved in the modding community. Having made mods for Skyrim, as well as having used and installed over 400 (only about 100 on at a time), it's safe to say I enjoy them quite a bit. On top of that, obviously PC has it's advantages in many other ways.
Looking above to your video you linked Pave Low, while the game does look extremely stunning, I just couldn't deal with that FPS loss. Which is what concerns me with some modders these days. While it's favourable to make your game look good, it's actually important to make it playable. Even with their very decent rig, there's so much FPS loss that to me, the game would be unplayable.
In saying that however I may actually try out some of those mods for GTA IV, my main issue with the game was the dull tones and terrible use of atmosphere, so perhaps I'll come back to it now and play with my pad on PC. Imploring some of the advantages I see with the mods included in that video. It does look stunning, and while I do have a GTX 770, I'm not sure even my rig would handle how much load is coming in with those mods, so I'll trim it down a bit.
Truth is, when I left Xbox for PC (and all I kept was my gamepad), I could never turn back.