Why?
Because leveling a BE gives you 3-10 stacks of Small Eggs, easily.
And they are selling for 15-20G on my server (and this on Horde side, where my level 10 BE Mage is my only toon).
Now I'm just pissed that I made 60 Herb Baked Eggs before I realized, lol. Add in my herbs and I'm sure I won't mind losing the bank from my main.
[EDIT]
This kinda reminds me of FFXI. One of my favorite farming methods back when the economy wasn't god awful was to level my mules' jobs to 10. Crystals + certain items + lumber = lots o' money. Wasn't as good as high level stuff (and the difference in G per hour between a new level 5 and cap was much larger in XI than in WoW) but was still nice to actually be able to make money without being high level.
Edited, Jan 3rd 2010 1:05pm by idiggory