It's all about money.
PL attracts the most viewers these days and they get the most money. PL distribute equally meaning even though the big clubs bring in the most viewers they do not get paid the most money.
La Liga has two of the biggest clubs in the world, but they can't compete with PL in terms of money. Same with Serie A. Soon Leicester will be able to offer better deals than Real, Inter, Juve etc.
Uefa is corrupt to the teeth. Same with Fifa. Qatar got the World Cup 2023. Don't tell me they don't go after money. Fifa themselves proposed club wc. Btw. why should they be in charge of the European competitions and why should they decide how money is distributed? Here the clubs are taking charge.
I can perfectly understand the big clubs going for this. It makes sense and keep them as big clubs.
In all honesty I think the big clubs are just trying to shake up the current governing bodies. Maybe this will not mount to anything right now, but in next 5 years I think football world will look different.