While i do have a great dislike of Fizz, you bring up a valid point about his ult. I like that he has to use his ult in order to get a kill, since i think an assassin should need his whole kit to kill you...but that when he does it you WILL die without proper response.
These were the first four that came to mind.
Zed needs his ult, but it is targeted.
Talon needs his ult, but it is aoe and not a skill shot
Ahri "needs" her ult, but all the damage from it is targeted
Akali needs her ult, and it is targeted
The CD being close to that of the hougrlass however isn't really worth mentioning. Since Zed and Talon would have to deal with the same thing, and hourglass is a even better item against them since it gives armor and they are AD. Soooo again, not even worth bringing up.
I'd be fine with Fizz getting a bit of his Q damage back in exchange for his E getting a longer CD, but i don't see them changing his ult.
I DO however, find it very strange that they take out the DFG...take the damage amp off of charm...because it is similar to DFG...then do what they did to Fizz ult. Its strange.