So the short mags don't have a belt. WHOOPITY-DOO!!!!
So they come in shorter, lighter guns with shorter barrels and actions. WHOOPITY-DOO!!!
I think they're just a fad and once the craze over featherweight rifles burns itself out, people will realize these rounds, for all the hype, add up to very little.
As far as recoil goes, according to recoil charts, there really isn't a significant difference in the 'kick.''