The ESL was the clubs responding to UEFA / FIFA being a money making leech on them. UEFA / FIFA control their competitions to the extent that a stadium cant have a sponsor's name as it might conflict with their partners. UEFA are more than a controlling body they are a competitor to the clubs for sponsors. IIRC FIFA were backing the ESL as they are effectively rivals to UEFA hence the new world club championship, they want more income and are envious of UEFA and their UCL cash cow. The issue that I think fans had with ESL was, it being a closed competition and the effect on the PL, the envy of all the other major leagues. The ESL 6 weren't looking to leave the EPL, they wanted their cake and eat it, the proposed format would have affected the EPL making it a somewhat devalued competition secondary for the 6.
The ESL will now return in a modified concept, they will look at what the majority of fans were against hoping it will get less opposition, remember the PL6 didn't officially leave. UEFA modified the UCL in response to the ESL, with the new concept to be introduced next season, will it be enough? I somewhat doubt it