Essential Nodes.

Twysta

This has always been something I'm not comfortable with.
I've normally always had the characters, so it's not because of that. I don't believe in the design of it, especially straight after a new character release.
With the giant character pool now available and many duplicates I propose that you make the essential nodes a bit like that of Boss PvE events (which is much appreciated and a very nice feature) whereby you can use an instance/variation of the essential character.
So if the essential node is spiderman, you can use 1*,2*,3* or his 5* variants.
Granted I don't think this will "fix" all the gripes I have with PvE and scaling but it might go some way to alleviate it.