Some players have serious issues with the Lucky Islands texture pack, which only contains 1 texture
Imagine having a texture pack for Battle Zone with 50 textures
The games now fill up relatively quickly due to the game being brand new, in the future, players will without a doubt play it less, adding a rescource pack to Battle Zone could lead to even less players
Next to that all, if they would retexture all guns and maybe even more, that wouldn't really feel like Minecraft anymore