Hey, if you don't use the index then don't use the index. Use git commit -a. If you wan't something like the index in Mercurial you have to specify which files you want to commit, or which to exclude, which IMHO is a lot more tedious and error prone. Then again I haven't used Hg in a couple of years, could be they have something like the index now.

Rebase is a hack? Rebase copies a series of commits on top of an immutable history at a certain point in time. This allows you to deal with merges a single conflict at a time, instead of dealing with all the conflicts at once with a merge. It also allows you to avoid cluttering your history with useless merge-commits when just syncing with another repo.

Merges have their place. I use them whenever I merge branches, using --no-ff so I can attach a "Fixes issue #77" in the merge commit message. Of course, before I do that, I sync the branch I'm merging into, then rebase on top of that (to have a clean merge). I might also rebase --interactive to clean up the commits of my branch, so that the history is as easy to read as possible.

Comparing rebase to rollback is wrong. Git has rollback (or revert) as well, and it's used for other usecases, like when reverting changes on a public branch (where rebase would fuck it up for everyone).

I'm sorry, but your comments make it sound like you don't really understand Git.