Hi Res Texture Pack

[Colorful]

Probably something along the lines of
>Dev team is small
>Different priorities
>Server limitations jk

None of those apply here though, the textures are created in a very high resolution and then scaled down and made ugly. They don't delete the old textures willy nilly as that would be incredibly stupid for a multitude of reasons, one being they could reuse those assets for future content (a dirt texture would have many uses I'd imagine). But if you mean that's the answer they'd give us, that's likely...

[CGMidlander]

None of those apply here though, the textures are created in a very high resolution and then scaled down and made ugly. They don't delete the old textures willy nilly as that would be incredibly stupid for a multitude of reasons, one being they could reuse those assets for future content (a dirt texture would have many uses I'd imagine). But if you mean that's the answer they'd give us, that's likely...

Just because they have the textures on hand, doesn't necessarily mean they can plop them into the game without any forethought.

If they include the textures into the client by default, then it would increase the client size dramatically, which may be a problem for some users.
If they make the textures an optional add-on, then they'll need to do additional validation and provide support for problems that may arise from it. (Failure to install, incomplete install, bugs...etc.)

Of course, there may be other possible factors too, but these are just a couple reasons off the top of my head.