Two of the games wouldn't necessarily change - BYU would still have USU and BSU, I'm assuming, most (every?) year - depending on how divisions are broken up.
BYU could still schedule a couple of P5 schools each year while in the MWC. And I assume there would be some leeway to adjust conference schedule around what works for those teams. Seems like most years early works better than later.
And November games against Wyoming, CSU, AFA, UNM, etc. are probably at least marginally better than November games against Idaho St. and Liberty.
So it might be somewhat better for football for the team. But I'd say it isn't necessarily better for the BYU fans. TV exposure would be reduced - so fewer fans could see games. And BYU has enough fans in enough places that being able to travel for more than just 3-4 OOC games a year is nice and allows BYU to hit a variety of regions each year.