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.
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