I imagine this is controversial but I actually love that we have to collect prebis items for the next raid tier while still wearing full raid gear. I think one of the best parts of classic is getting those key drops out of ubrs or scholo and this system is replicating that feeling. I feel rewarded for playing the game! Random drop dopamine! Oh I didnt get the key piece I needed? I can just get a better version in naxx so the rng doesn’t feel harsh.
I figure this was likely an intentional design decision so good to the team for implementing this!