There were 2 instances of big platforms creating problems in the last few years:
SourceForge chose to replace installers with their own and added ads/additional software to them
Google Code shut down (to be fair to them, they made it easy to migrate to GitHub)
Also, GitHub (as opposed to Git) isn't free/libre.
So, as long as Wildfire Games has the manpower and money to maintain their own, they should stick with it. And a webserver maintainer isn't necessarily an application programmer as well, so maintaining the thing probably doesn't take that much away from development time.
Personally, I'm a big fan of Bazaar because the commands are dead easy, but sadly their tools are seriously undermaintained these days.