It changes a lot. You are switching at different frequencies and although the currents are smaller, there is an increased cost if you want to do it efficiently and not have too many losses.

But anyway for consumer products this is unlikely to happen because it would force users to get new power supplies which would reduce their sales quite drastically at least for the first one they make like that.

The solution would maybe be to make a low volume 48V card and slowly move people over it showing them it is better?

Anyway this is clearly not a case of "just use X" where X is 48V. It is much more subtle than that.