I've owned bikes in sizes with standover heights ranging from around 30 inches up to around 34 inches. My slacks have a 32 inch inseam, and my leg length, from the floor to the public bone is about 34 1/2 inches. That means that when I stand flat-footed over a bike with 33 inch or 34 inch standover, the top bar is brushing lightly against the crotch of my slacks.
A bike with a top tube that brushes against the crotch is too high, IF someone is buying a bike for the purpose of standing flat-footed over it. But, such bikes fit me perfectly for riding. And, I have no problem getting on or off, or putting one foot down on the pavement at a stop light.
If I was buying a mountain bike for riding off-road, I'd want more clearance. Lots of opportunities in trail riding to come into contact with the top bar. But, on a road bike, riding comfort, not standing comfort should be the key factory.
Thirty years ago, when the average American male was about 5'8" or 5'9", the average bike was size 58 or size 60. That was when shops fitted bikes for riding, not for "standing over".