Please, Git maintainers, don't listen to this guy and don't ever change the current behavior. I've come to rely on staging my commits incrementally.
I really care about keeping a pristine history with isolated and understandable commits. Being able to commit pieces without including temporary code or debugging comments is invaluable to my workflow. I want to be able to modify source code without worrying about any piece of it getting committed accidentally. I also want all edits I made, including uncommitted ones, to stick around until I explicitly remove them.
Maybe Mercurial can do this also, but Git has been almost completely do-what-I-mean with regard to making sure I don't lose any changes or confuse myself about where they went.