I'm not a fan of Bitbucket for various reasons, but your point is well-taken - I tweeted them just now myself:

>generally like the octicons, except (a) some are too detailed, and (b) the colored bkgrds are confusing. (still a fan!)

Then again, I'm pretty sure GitHubbers will be watching this thread. ;)

My comment on their "Making of" blog post expressing my criticisms was deleted without reply, how friendly!