My criticism is precisely that feedback was lacking. The assignments were only graded on submission - there was no feedback there (likely because every student worked with different data so going in-depth would have required the grad student TAs to spend too much time per student digging in).

I don't agree that feedback during lecture is valuable or low-latency as you say - not with 100 students attending. It might work to ask a clarifying question here and there, but again - you're only in a position to take advantage of that if you're already comfortable with the material and are generally keeping up.

Books are different than lectures, sure, but I don't think there's much difference between attending a lecture with 100 students, or watching one online. Indeed many people claim the online way is better, since you can rewind and skip around, pause and lookup references, etc...