Standover height is not a good measurement for bike size. When sitting on my saddle at the correct height I cannot touch the ground. My legs are 2" too short. I do have standover clearance on some bikes- but not all. I just lean the bike over before I put a foot down and yet to have a problem.

I am short and I do use Compact frames- but for some of us- that will still give negative clearance. But my bikes fit me and they ride well.