A sense of direction is rather useful when working on a tileset, especially with several people. I suppose it's okay to deviate a bit in the name of artistic freedom, but having one coherent overaching theme for the tiles makes it easier to work on a set.

Of course I haven't contributed anything yet, so maybe I should shut up, but then again part of the reason for that is that there seem to be a few conflicting views on what direction to head in with the set and I'd like to wait until that's clear before making an attempt.