Why was Warp (and other effective powers) not brought over?

I asked the lead designer once on Twitter and he said power stripping abilities were included in certain biotic upgrades. I haven't found one that strips armor, but biotic pull can be upgraded to take away shields.

I think the main reason is because there are no defined class borders anymore. Warp was useful against armor and for combo detonations, but you also have access to fire powers and other detonators, so maybe it felt redundant.