From: United Federation of Planets
Like I said, far too many exceptions to this ideal RB height. You say Payton, I say Brown. You say Sanders, I say Dickerson. You say Tomlinson, I say Allen. You say Faulk, I say Harris. You say Thomas, I say Simpson, etc...
I don't think height, or lack of it, matters that much. Far more important is foot speed, explosion, low center of gravity and strength. Sure, generally speaking, smaller guys tend to have better foot speed, but that's not automatic either.
As far as being less visible to the defenders, why not have 5'-2" RB's dominating the league?
Arm length aids in blocking, receiving and ball security.
I think you are missing a very important aspect of a very good RB and that is superior vision. They see the hole sometimes before it forms and they use the foot speed, explosion, low center of gravity and strength to run through it. Micheal Bennett has all the things you mention but had no vision...thus happened a lot. He looked like he had no idea where to run.
In 2016, Clinton's underlying (and sometimes overlying) message was something like this: Trump is awful and you will never vote for him. And I am the only other person running for president.