> Configuring a database and access to it
Welcome to the world of server software. I think everything web app I've ever installed required database configuration. I take it you've never installed Wordpress? Or Roundcube? Textmate? Gallery? OpenPhoto?
I agree that other parts of the installation are annoying (python2 link, which isn't standard [1]), but the configuring a DB is very par for the course.
The special system users part annoyed me at first, but I realized I'm creating ssh access for git and so in that light it makes a lot of sense to create a new user. On the plus side, gitolite lets you have a ton of users that can use ssh to get the code without having a user account for each one, so it's a win over the long haul.
[1] On my Debian system (should also work with Ubuntu) I solved this with:
sudo update-alternatives --install /usr/bin/python2 python /usr/bin/python2.7 7
This lets the package system know about the symlink instead of just putting some random symlink in a package-manager controlled directory.