And why 10mm?
Ammo availability is less than 9mm or .45, that's true. But to reload for, it's easy enough. To order ammo online, its easy enough. And this last year, more stores have it stocked. In Utah, Cabellas and Get Some both have a rather decent selection compared to last year.
But the increase in power and penetration is incredible for a slight increase in felt recoil over the .45. I mean, in some guns... I don't feel a difference, I really don't. So with that increase in power... with an increase in magazine capacity... that's a win.
Yes, it's non-standard. But it should be the new standard.