Fizz's identity

First off I'd like to say that despite Fizz being the weakest he's been in a long time, I happily main him right now. The current PBE changes to Fizz make me wonder what Riot wants to do with him. (They are giving +0.05 AP ratio buffs to his Q and W, while reducing the base damage on his W's active effect, and making Chum the Waters only amplify magic damage). It seems to me that Riot is trying to solidify Fizz as an AP assassin and remove bruiser Fizz as an option.

I don't think that Fizz having the option to build as a bruiser is problematic or OP at the moment compared to AP assassin Fizz. And let's face it: Fizz's kit is better suited to a bruiser than an assassin. He is handicapped by having no ranged poke or means of ranged CS, his passive gives him some tankiness, his W is an auto-attack enhancer, and all of his other abilities are used mostly to help him stick to his target in melee range. There's nothing wrong with that. He's a healthy hybrid champion, and there's no sense in trying to strong arm him into a strictly AP role in his present state.

Conversely, when Fizz IS strictly an AP assassin, he is very binary in his strength. Prior to his 5.2 update, Fizz could Q + aa + E a target and kill them outright similar to Le'Blanc. His burst was higher but his AA's were weaker. When that's the case, he has to be able to instantly kill his target or he's a worthless dead fish in team fights. That's because unlike every other assassin in the game, Fizz has no non-ultimate form of ranged damage or CC.

He's much healthier in his current state. He has some burst, but most of his damage comes from his auto-attacks. With some AP scaling on his auto attacks and the natural synergy AD items have with auto attacks give him a uniquely diverse range of build paths. He is perhaps the only champion in the game who can successfully build truly hybrid (EX: BOtRK and Zhonya's).

Lowering the base damage and giving him a better AP ratio on his W will do nothing except restrict Fizz's viable build paths (and make strictly AP Fizz players happy). The change to his ultimate is even worse. Losing the 20% bonus physical damage would make items like Trinity Force and BOtRK on Fizz barely viable since their passive effects would no longer benefit from it. My question for Riot is simple: Why? If Fizz is already perfectly viable as both as AD and AP, why break what isn't broken?