You don’t need it. Blizzard won’t make $ from it. It will cost them to implement. They will lose people like me as customers when there is nothing in a current expansion for me. Plus it will remove the reason to actually work on things when the content is current, if you can just wait a couple of expansions and get it all for free anyway.
I agree with you.
However Blizzard refuse to make raids from 2 expansions ago easily soloable. They definitely won’t do it.