I already have two alchemists, both maxed out. All my lvl 80 alts that still don't have at least one main profession I'm powerleveling them on Alchemy.

Main reason if not solely is:
"New unique material used by nearly all high-level recipes will be created by alchemists on a one-day cooldown."

Source:
http://forums.wow-europe.com/thread....Id=13200229268

Between azeroth fly, high speed flying and getting the new level on professions, we'll need something around 5k per toon on Cataclysm very start. That's a lot of money (well for people like me that hates the whole AH deal... I always just have enough money for my goals ).