Now that is important, but how would you go about changing it? Making the textures look like they would on a flat floor would mean that the textures would have more of itself jammed into one grid part, because there is a larger area there to cover.
Randy said (long ago) that the code for not stretching slope textures is present, it's just commented out [slaps randy w/ dead fish]. So it should be an easy job...but I'm not a coder (well, I do BASIC pretty well, but that's it)