I actually think .25 has had it nailed for a long time, in the trade offs of bullet weight and associated recoil, expansion ratio and throat / barrel life, and full use of small to moderate and efficient case capacities. That is to say once the bullet tech and twist rates caught up.
120-130gr range is quite an ideal bullet weight for reachy game animals, goats, sheep, mountain or open country deer, pronghorn, etc. There are reasons in my mind manufacturers and competitors have bounced back and forth between 6mm and 6.5. Everything is a collection of compromises, and the .25 bore has one of the best collections going.