Posted By:
Scott Gross"Does anyone know why .... ?"
I have to go with the Philosophy 101 answer: Why Not ??? 
They're strip cards, and from my limited experience, anything goes: reverse images, assending/decending numbering, no numbers, captions, etc. If strips get more popular (and they will, but only to a certain level), we'll see more and be able to answer more about them.
w512 Goldstein, with and without number (he is the only w512 I've seen without a number):
