Definitely agreed - I use BitBucket to store some private projects, which also means I don't pay them anything (yet). Seems not terribly profitable - I keep a backup elsewhere assuming Bitbucket will go down eventually from lack of funds!
Seems like Bitbucket was acquired by Atlassian for two reasons:
1. Free DCVS hosting as a free perk to existing customers, with tight integration to existing Atlassian products.
2. Free DCVS hosting to non-customers, with the hopes of converting some to the Atlassian suite.