For some reason, minecraft 1.8 is still used on some servers, and it would be nice if we could support this version. But, since resourcepack predicates were introduced in 1.9, this is not possible for vanilla minecraft. Luckily, the popular Optifine mod has its own system of resourcepack predicates, which might even be present in its version for minecraft 1.8.

Still, this would be quite some work since we need to look into this system, and do #2 first. Also, only players who installed Optifine will see the textures, so it's quite limited.

Since MC 1.8 is even more ancient now (and isn't used that much globally), I won't be adding support for it.