Matt, this is a can of worm's not often discussed but is recognized by serious vinylphiles. There are turntables where the VTA can be changed on the fly to accomodate the angle of the cutter head on the lathe that cut the disc in the first place (not always the same, but often known by true vinyl experts) as well as the thickness of the vinyl. Some like to use the adjustment on the fly just to fine tune the sound. VTA changes with the stylus forces selected as well as the thickness of the disc. The angle of the stylus on cartridges is not standard. And the proper VTA does make a real difference to folks who have the listening skill to hear it. It is most easily discerned by differences in tone and soundstage image. Most arms allow for static adjustment, but because it is complex and equipment dependent, some turntable/arm manufacturers (well known ones) don't even provide for it at all - you just have to be sure to get a cartridge, that is the right heighth and has the proper stylus angle to begin with to achieve what in effect is a good sound most of the time. If this subject really interests you i would chase down some literature on it and read up.
