Bazaar development can't do user interfaces. Any time "shut up and show me the code" isn't the correct response to the problem at hand, the development model melts down into three distinct failure modes:
1) Endless discussion with no resolution,
2) Fork to death with everybody implementing their own vision and then no way to merge them back together,
3) Delegate the problem to nobody by either A) separating implementation from interface and focusing on the engine, B) make it so configurable the fact it has no sane defaults is now somehow your fault.
Bazaar development either needs empirical tests so everybody can agree on what "good" looks like, or a Benevolent Dictator For Life who makes the calls on aesthetic issues.
Trying to do a GUI collaboratively is like asking wikipedia to write a novel. Too many cooks spoil the soup by making it taste bad, not by causing it to lack nutrition. We've only _selectively_ overcome brooks' law.