If you're using something hosted in SVN you're at the mercy of the repository host, since the project history lives in that one location. If they go walkabout / get hit by a bus / take their ball and go home you lose the project's history unless people have been maintaining their own mirror of the entire repository. Whereas with git (or hg, or any of the new distributed systems) every contributor has the entire history and every repository is just as good as the "master" as soon as you've pulled in any remote changes.

So that's why people like git :-)