oh how I remember the days three years ago when I tried to explain these things. I'm very happy to see such ideas and discussions beginning to infiltrate the Western/American otaku culture!!
By the way, yes the first Moe-tan rather sucked in its English usage (which surprises me since it was proofread by an English professor), but Moe-tan2 is written in great colloquial English. You should give Moetan2 a try, especially the story is pretty sad and heartwarming.
As for "-tan" culture...there is no "tan culture." It's all part of nijiura and gijinka, an aspect of moe~.
Also, you might want to check out the new anime
Binchoutan which airs today.