I was in the middle of writing a meme response, but whatever.
Remaking popular Gmod gamemodes would IMO be a bad idea for several reasons:
a) People can and always did play them in Gmod, and there'd be zero reason for them to move onto TU (a 15$ game). The remade versions would quickly become a ghost town.
b) Even if they got remade in TU, the Gmod versions would receive a lot more care. I'm not saying the devs aren't working hard enough or anything, but compared to a popular Gmod gamemode, a single part of TU receives a lot less attention (one new map every few months at best), meaning there'd be even less reason to play the remade gamemodes.
c) It'd take manpower and resources from other projects. I'd rather see the devs work on new, original content, rather than copying whatever's popular and working perfectly fine elsewhere.