Our organization uses some software to deploy users to servers (and doesn't allow other users than those). Sadly, it's not possible to use more than 8 letters for a user.
So, atlbitbucket isn't allowed (confluence btw, isn't, too) and we use user git for bitbucket.
Anytime, when I upgrade Bitbucket, I have to do the upgrade and chown /opt/atlassian/bitbucket, /home/git/application, /home/git/repositories just because your installer gives them all to atlbitbucket.
this is a little effort but also, a high risk. (best neccessary work is no neccessary work..) So why isn't it possible to install with a --bitbucket-user option?