Proper enterprise support requires customer representatives, phone lines, sales people. All that is expensive and requires capital.
Of course, this is just a wild guess. I have no firsthand information.
Some specific gripes included very slow support response time and poor options for installs (vm based only). There were others but it boiled down to the ops guys asked to set up and maintain the system weren't happy with the way they were treated.
I don't think 'going enterprise' is good for the culture of any company, but if they want to do it, they definitely have to kick up their game.
Trying to win on purely technical merits won't work. Being unresponsive especially during an evaluation is the kiss of death.
I worked for a smaller outfit that sold to enterprise sometimes directly and sometimes through larger partners (CA primarily). Except when we told them they had no idea of our size.
But we still pay for it, because what else is there? :)
That might be wrong, but I'd need to see a lot of evidence first.
[1] http://blogs.atlassian.com/2011/11/why-we-removed-wiki-marku...
(Which now supports Git: http://blog.bitbucket.org/2011/10/03/bitbucket-now-rocks-git...)
There's also the option of Gerrit which puts most of this in a single WAR (not gitweb, though as with gitolite the integration is documented), with a code review workflow on top.
Disclaimer: I work at Fog Creek.