Why are you bringing up graphics? It has nothing to do with my argument. There are hundreds of games with deliberately retro graphics and modern controls. Why can't VotV be one of them?
Also, why are you bringing up Half-Life 1? It doesn't use the Source Engine. It uses GoldSrc, a modified version of the Quake Engine. I know that Half-Life recently got an update for its anniversary that tweaked a bunch of stuff to make it more authentic to the original release, including removing the 'fast weapon switch' option, but I think that change makes the game worse and I honestly have no idea why it hasn't been re-added yet. I have to use scripts to get around having to deal with the slow, clunky default weapon switching.
Gmod is is less of a game and more of a creation tool. It needs more complex controls to allow players to manipulate objects in all the various possible ways they can be manipulated. But, because you don't have god tools in an actual game, all that complexity isn't needed. For example, in TTT, to pick up a weapon you look at it and press the use key. To drop it you press the 'drop weapon' key. Easy as that.
If Voices of the Void had more streamlined, intuitive controls, how would that hurt the game experience?