For me, it’s about wanting to see 4e design iterated and improved upon. If I want to play 4e I can play 4e. I moved on from 4e though, because while there are aspects of it that I think got thrown out with the bath water, the overall experience does feel very 2010 to me. What I want is a 2019 evolution of 4e. Something that takes the best parts of 4e and brings them into a more streamlined, approachable, modern system. I want the 5e from the alternate universe where 4e sold gangbusters. And the 5e from this universe is probably the best baseline to work from to make that. Certainly it has a broader pool of potentially interested players than “hey guys, want to play my heavily houseruled version of 4e?”
I assume you've looked into 13th Age? It's very much, in many ways, an attempt to be exactly this.
It didn't quite hit the sweet spot for me (because it goes all-in on the TotM among other things) but it seems to work for a lot of people.