Do you think the number at the end, with Rachel and Finn getting the lead singing roles and the minority kids in the background again is deliberate on the writers' part too?

I think most things Sue says are deliberately offensive; I think Finn is deliberately written to be rather dense; I think Rachel is deliberately written to be annoying.

But I can't tell if they're not giving storylines and solos to the minority characters so they could highlight their own fail in this episode or if they're following the patterns of most other shows out there (because that's the result of what they're doing, so far). If it's intentional, perhaps contributing to the fail is not the best way to address or somehow subvert it?