I was going to make a post about how Fizz's E is just too cheap for him to use(compared to similar skills), but to be honest, you're right Penguin. He is melee, and that's the cost for his E. Ultimately, these changes are in line with Riot's attempts to shift the meta. With the removal of DFG, and the stated intention to move Kat into more a highly mobile magic damage fighter, changing Fizz's skills from upfront burst to slightly more sustained damage is quite logical. Is it a nerf to Fizz, possibly, quite likely actually. Will it open new Fizz build paths and allow for more diverse counterplay, (outside of the positioning balance game) who knows? I think that's what Riot was going for though.
And, while the damage no longer amps over itself, it does apply instantly, which can be very very big when it comes to assassinating targets. It seems like fizz might move into the fighter role, in a position to clean up damaged bruisers, and pseudo assassinate carries. The reduced burst will require Fizz to stay in battle for longer if he wants kills, and that is clearly Riot's goal here. Is that a nerf to Fizz, hell yes. Does riot want to move away from the 100-0 with little to no risk assassination methods that are currently around, yeah, yeah they do. Will new Fizz suck? In terms of being able to singlehandedly (and without significant defense) remove 1-2 members of the enemy team from the game when fed, likely. Also Fizz has like a 70% ban rate down here in gold. I would love to actually get to play Fizz sometimes. TBH I get the feeling this will improve some of Fizz's mechanics, even if he won't be an hyper assassin anymore.
Time will show how bad this possible nerf will be, but for now it's all PBE speculation, so who the heck knows what the final numbers will be. Plus it's not like fizz is Eve, someone at Riot likes him, I doubt he will get nerfed so hard he falls to subpar levels.
PS: I was agreeing with you UXLZ, my apologies for being unclear.