I think you are misjudging the "common case".
The front camera is 7MP (close to 4K) and records 1080p. I don't know of any videoconferencing software that uses more than 1080p, and there's always massive compression applied anyways which would defeat image improvements. The quality is more than enough.
There's also very little practical issue with it being on the side when in landscape mode. It just means that your eyes appear to be looking sideways rather than downwards (arguably an improvement, as eyelids don't move down -- much closer to how people actually look in an in-person meeting when not looking directly at you) and that your head is about 10% off-center. So a non-issue. I've never seen anybody even notice it in a conference call, much less complain.
Finally who is taking selfies with their iPad? That's what phones are for. It's too big to hold with one hand.
The common use case for cameras in the iPad Pro is actually the rear camera. iPads are being increasingly used as professional tools in shooting production-quality video as well as all sorts of other commercial applications.
So I think the balance is quite right.