Usability question

When starting with git people almost always ask some variant of "how do I know whether this option should be prefixed with dashes or not?" i.e. git reset --hard vs. git stash save --patch, which coupled with other path, sha and treeish args make things a bit more confusing.

Not sure if this has been discussed before? If it has point me at the discussion and I'll go look at it -- no need to read further.

And people stop asking the question after they get used to git - but that's not the same as being usable.

Out of 60+ commands, most take the form git <subcommand> [--option] and a few take the form git <subcommand> subsubcommand [--option]

(a quick scan gives: bisect,bundle,reflog,remote,stash)

My questions:
1. What is the distinction that makes the 10% special enough to get
non-prefixed options?
2. Is it worthwhile? Wouldn't it be better if to shoot for more
consistency / less complexity?

Rob