im going to play devils advocate for a second, but know going into it, i don't agree with the prestige system - just that my gripe is on the other end (similar net result).
i personally have NO problem with a team like this capping out at an A without a championship or two. the reality is butler is still not kentucky or UNC or duke, and even if they make 6 more sweet 16s in the next 6 years, they still won't be. even michigan state isn't kentucky, and they have been great for a long time, in a major conference.
however, its not just something i would limit to marshall. vanderbilt, clemson, michigan, illinois, texas - schools like that, from big programs to smaller ones, who are not traditional basketball powers - i don't think they should hit an A+ with your resume either. the reality is, none of those schools today, except maybe (and somewhat inexplicably) texas (due to rick barnes having some recruiting mojo magic), none of those teams really have much recruiting advantage over a gonzaga or xavier or similar. the problem is, in HD, there are maybe 15 A+ schools in a world - absolutely ridiculous. on my scale, girt, id give you an a-, but there'd probably be only 10 schools ahead of you. you should still have a disadvantage to the elites of the world (which again, there are too many of), if they are being well coached. and you should still have a disadvantage to a program with a similar resume with a title or two sprinkled in - thus, there needs to be room for schools to have an edge over you - so i argue your a- is not the problem.
the real problem is all those schools ahead of you. i have south carolina, and have benefitted someone from this ridiculousness, i made a couple 2nd rounds and that got me to an a-. its insane. the simple reality is south carolina and marshall, they don't have much benefit from their brand. maybe with your resume, south carolina should be an A to your A-, but no, they'd be an A+. neither has a strong brand, and you can't sell recruits off that name. its more about the coach and recent success for just about all the schools in the world. hell, maybe all of them. i mean look at kentucky under tubby smith. they were good by an absolute standard, but not relatively, and recruits weren't just coming to kentucky because its kentucky, you need more than that - they should have been an a- or something in his later years - but in HD, they'd easily be an A+. thats the problem, baseline prestige is just too much a factor in propping schools up. i dont think it is too much a factor in holding schools back though (at least not schools with c- baseline or better). your program isn't A+ material in my book, somewhere in that borderline a-/a range. but im sure if you pick out the A programs, in my ideal system, 80% of them would have lower prestige than you. so i agree its a problem - just i look at it a little differently.