The problem I have with "git commit" committing everything dirty by
default is that it encourages exactly the wrong kind of behaviour, ie the "commit it all in one go without thinking about it".
And "git status" really isn't that hard to type, and it will tell you exactly what you've already marked for commit, and what you have dirty in the tree but isn't marked for commit yet.
So I think the "git commit <file-list>" thing is very convenient, but it's
convenient exactly because it's concise yet still precise and doesn't encourage the "just commit whatever random dirty state I have right now" mentality.
And if you have more than a few files dirty in your tree, I really think
it's much better to do "git status" and think about it a bit and select
the files you do want to commit than it is to just do "git commit" and let
it rip.
Now, I could well imagine adding an "--all" flag (and not even allow the shorthane version) to both git-update-cache and "git commit". So that you could say "commit all the dirty state", but you'd at least have to think about it before you did so.