It's not licensed to the campus of UMass Boston, it's licensed to the city of Boston...as in THE WHOLE CITY. (or, in the case of their repeaters, to those cities) AFAIK, WUMB doesn't receive any formal subsidies from tuition or student fees, either. Exactly what reason should WUMB have for explicitly putting sub-standard programming on the air simply because it's produced by UMB students? And yes, it would be inherently be sub-standard because there's zero classroom curriculum at UMB to teach them...and since WUMB isn't getting any subsidies, why should they absorb the burden of teaching students?
BTW, if you said that since UMB's mission is education, and since there is no radio or broadcasting curriculum at UMB, then UMB should not be in the business of owning a radio station...that's a very valid argument. I wouldn't necessarily agree with it, but it's entirely valid.