The Whys:
AEG - Honestly, difficult to say. Not interested in Rokugan or Spycraft. The sourcebooks I've glanced through in the store and mostly been left wtih a feeling of "eh..."
Atlas - Been meaning to get Nyambe, embarrassed that I haven't yet

Probably would have grabbed some of the Penumbra stuff if I didn't already have a flood of modules with Dungeon and my old AD&D stuff.
Avalanche - Quite bluntly, it's the covers. I a) am very turned off by that sort of advertising, and b) won't have something in my house that everytime my wife would see it would roll her eyes and mutter about elf porn. Sorry, as truthful as I can be.
Bastion - Another embarrassement

Been meaning to get several of their products, always seem to get distracted by something else when I'm in the store. *note to self: must make and take list*
Fast Forward Games - Only seen the Swords and Rings book in my FLGS, once again left with a feeling of "eh..."
MEG - Another of the 'been meaning to get'.... Where's that list at?
Pinnacle - I take a look at Deadlands everytime I walk in the store, it'll snare me eventually... I've just gotten to the age where even though I have 10 times more money than I had in college, I have a hard time justifying buying game stuff I know I'll never get the chance to play
RPGObjects - Never seen any of their stuff in my FLGS before. Darwin's World does look interesting, but see above under Pinnacle.
Troll Lord - All I've seen of theirs is the Gygax stuff, another feeling of "eh..." unfortunately.
/em gnarlo!