To be fair, a closed league for the teams that have all of the resources and influence is what North American sports is.
Ehh I really don't think it's the NHL/NBA equivalent everyone wants to make it. It's more akin to the NCAA. Imagine if the top 15 college basketball teams just formed a pact that they'd play the season as usual, but no matter the results those 15 plus 5 invites would be the NCAA tourney every year.
The biggest issue structurally (setting aside the FU to fans) is it devalues and completely changes the domestic league without consultation.
Right now City and United are the only ones statistically able to win the title. And its a long shot for United. For Liverpool, Arsenal, Spurs and Chelsea, there would be asbolutely nothing to play for with a Super League. For some of them the domestic season would have been meaningless for months.
I guess West Ham, Leicester, Everton would be battling for some CL spots? Mixed with a bunch of aforementioned teams that have nothing to play for. How obnoxious would it be for Leicester to finish above everyone bar United & City, but not get into the top league?
The big advantage to the way it was setup was that you could argue that probably 15 teams had something to go for all season, even to the end. Top 4, plus 6-10 were within 5 pts of Europa spot. 3 relegated plus 2 just snuck by.