Why? BitBucket is superior in every respect, plus importantly they give free private repos for every user. No price gouging like we're seeing with GitHub.
It's cheaper and has private repos for free and that's it.
The UI is clunky and the community is much smaller than Githubs.
I also don't understand why they try to sell it with the Jira integration as if it was a good thing. The only people I heard saying good things about Jira and this marketplace where working on companies that sold stuff there.
It's not really price gouging. GitHub's product is GitHub. Atlassian's product is Jira, which nets them a tidy penny, and BitBucket is their loss-leader value-add that they can use to undercut GitHub.