One thing your S should be aware of--Greeks are strong at IU, stronger than you might think from the percentage of students who belong. My impression--which you should check because my familiarity was a long time ago
Not the case, or out of date, or based on the usual silly DCUM hearsay. My niece graduated from IU last year (was OOS, had a wonderful time there, now in grad school), had no interest in the Greek system, and said it 'was there' -- just like the performing arts and sustainability groups and others -- but had little impact on those like her who didn't want to be a part of it. She said she and her friends would go to one or maybe two Greek parties a term, kind of like she'd go to one or two football games a year.
There are 48,000 students at IU/B (and 80,000 residents of Bloomington -- a small city with a lot to offer). The link says "over 8000" are part of the Greek community. The other ~40K aren't sitting around feeling marginalized. Of course, this is DCUM where some pay lip service to the notion of diversity but are afraid exposure to different kinds of people might contaminate them for life. If that's the issue, then sure, IU and indeed any Big Ten school (or midwestern university, or 'red state' school) probably risks contagion. For other kids, expanding one's life experiences -- not just credentialing -- is supposedly one of the objectives of higher education.
As for IU, it isn't MIT or Columbia, but if a student with IU-level stats wants a big (or Big 10) university experience, it's a great option. Good programs, a diverse student body (and relatively high OOS ratio), and with the added benefit of being located in one of the great college towns and (since complaining about colder climates is an obsession on DCUM) not too far north.