What you are saying is "In order to fix tank Ekko, change his playstyle entirely so Ekko mains have no fun". I really don't appreciate this.
Tank Ekko now a days doesn't work unless he counters the enemy, or he is fed. So you could be saying "Well he shouldn't be able to do it at all!"
Lemme tell you a story, back in season 3 I faced a full AD veigar botlane. He carried. He got fed off of our botlane and snowballed, the AP from his minions and the AD from his build made him a hybrid damage monster and he literally 1v5ed. This can happen ANYGAME unless he doesn't get fed.
Anything works if you are ahead, I won a game as full AP garen once.
Don't act like you know how Ekko mains play, because you don't. Ekko mains don't use his Ult to escape situations most of the time. 20% Escaping, 30% Initiating, 40% Damage, 10% Heal. You making it a longer rewind will make it EVEN HARDER for us to time our ultimates correct and COMPLETELY screw his synergy with Zhonyas. Lets say it had a 6 second rewind, and we wanted to use it as AOE damage in a teamfight, that means I need to live for 6 seconds in a teamfight WITHOUT THE ENEMY MOVING. They will be all dead by that point, also the ghost for his ult will be OFF HIS SCREEN if it lasts more then 6 seconds. Also "More damage while in W field" is the WORST THING that you could do to his W, Ekko is all about going in, using your CD procing passive and REPOSITIONING. You can NOT stay in a field while repositioning, it will literally make it so your passive is useless beyond the damage and it will lower the depth riot put in his kit.
Basically if these changes happened the people who played Ekko before religiously, will now have to abandon their style, since no other character plays like Ekko. Except maybe Yasuo, but you all are screaming for a Yasuo rework as well.
When I heard Ekko might get reworked in the assassin rework I cried. Everyone saying "LoL isn't fun anymore" I have to say it is for me because of Ekko. If he gets reworked I will have to quit league because I do not have fun on anyother champion.
One last thing, can you think of the position I am in? How do you think it feels being flamed everygame for playing the champion you main, just because people think he's broken. How would you feel if you are called "no skilled" everygame just because you are playing your main? How would you feel if you get camped everygame because you played your main? How would you like it if your main is PELTED with nerfs and you just have to accept it. How would you feel if you made a board post about how much you like Ekko, thanking riot for making him and you are SPAMMED with hate and downvotes just because it's Ekko?
I only have fun while playing Ekko, and all I ask is for more seconds to play him. I am legally changing my firstname to Ekko when I get the chance.
Sorry for the rant, I did not mean to insult anyone in anyway, all I ask is you read it all the way through.