One conference championship in 15 years. Much of that time was after the conference was weakened. That is pretty mediocre. Embarrassing home losses. Finishing 2nd or 3rd in the division constantly. Multiple losing seasons, one as recent as 2016. Marshall has not finished first in their division since 2014. Our current coach is 45-27 in conference. I wouldn't say that is stellar nor terrible. But, yes, mediocre considering two teams in our division was either IAA(and not a great IAA) and one never had a program 10 years ago. FAU and FIU really have no great tradition. WKU and Middle Tenn came from the Sunbelt and were not exactly world beaters. Mashall has only won their division twice under the current coach in nearly a decade.
As I have said, schools like FIU and FAU have plenty of resources to make themselves compete and frankly, don't need much to compete against a resource depleted and fickle fanbase of MU. You said that a few schools were FCS before, and as I have said once more, they are actually motivated with money and resources to move up to where we are. Unless we get an economic boom where we have money coming in more steadily over people unwilling to donate because goal posts aren't painted, MU will never have what they do, to compete.
Lots of offseason posts in the past were all about what CUSA teams were building, or doing, around campus to improve, people kept kicking around saying, "Well why can't MU do that?"
Then get upset and call MU a failure when they lose a game to these schools.