Hi Res Texture Pack

[Riardon]

Now that the PS3 version of the game is dead I can't see any technical reasons for this not being possible. It would certainly be nice

There are no technical reasons. Only "political" ones. Textures are just images. Single player games which allow for modding have seen "HD" texture packs made by single persons by themselves. If one person can do it alone unofficially out of the company then imagine what the company with budget can do. It's nothing for them. Basically they already render the game at much higher quality and then they gimping it down.
The only reason I can thing they turn a deaf ear for this is their policy with consoles. Some companies do not want to give much better looks to the PC version of their game just to avoid upsetting the console players who they will feel have an inferior version of the game. It's sound silly but there are such policies inside companies. This game's textures are far too low resolution for this time and age especially on a successful premium sub based game like this.
Shadows and reflections could also use some work and fixing. Shadows in particular are kinda broken atm (wrong/broken shadows and flickering issues).