I am all for ground level retail in this area, however BU is a college and their job is to provide academic/housing/dining/athletic/study space for their students, not to provide retail for the average Boston resident, just saying.
(a) Retail space is a major benefit for their students and (b) if they want an urban campus then they have certain responsibilities to keep: such as playing nicely with the city they're occupying.
The city has a vested interest in not being cut up into a dozen different turfs that wall each other off. And frankly, it's not in BU's long term interest to create such a turf. That is, if they have any interest in being an actual university and not simply a day-care center for 18-22 year-olds from rich families.