That's part of the point though. The less crafting you make possible via alts, or the harder you make it to aquire the recipies (... thus making it unlikely you'll get it on an alt) the more you increase the, well, "playability" of professions for individual players. If an alt can do everything I can do, I'm not particularly useful in regards to profession. Short of adding a limit to the number of characters per server (which has been done in other games) - or professions per server - there aren't that many ways to insure viability for professions for many players. Interaction requirements, is one way, Masteries, BoP recipies, rep recipies, raid recipies, lvl requirements for professions and so on, are other examples of similar systems. The only thing I don't get it why they're not taking steps to make it system-wide and not just enchanter-only.
Requiring interaction makes it hard for alts to be used as crafters though.
Speaking of character development via professions, there's one thing about gathering profession that keeps irking me. The new stat bonuses are great, they really are, but... My main alchemist has been an alchemist since way before TBC, and all of TBC. If I leveled a second character, as fast as possible, and got him to 375 alchemy as fast as possible, there'd be a difference. My alt would lack many recipies - BoP, rep, BoE, discoveries - so he wouldn't be able to do as much. Where as my herbalist alt... There's nothing I can't do on my herbalist alt I can do on my herbalist main, despite significant difference in hours invested. The bonuses won't really change that. But that's not really what's irking me as much as the fact as what we have in BC is less than what we had in vanilla.
Finkle's Skinner, Pristine Hide of the Beast, Onyxia Scales, Core Leather, Bloodschythe, Bloodvine... They certainly weren't huge things, but they were... There. A gathering alt was that just dinged couldn't help with all of that (ignoring the raid instace requirements here ) you'd actually need a dedicated and well geared practicioner of the gathering profession. I miss that, and I don't understand why they didn't have it in BC.