Meh. Virtually every comparable ability is point and click (Thundering Blow, Dragon's Rage, Heabutt, Condemn... arguably Crescent Sweep and Monsoon). It's not like a point and click knockback is something unique to Tristana that's obviously OP in every instance, and the ability's already been nerfed in recent memory. Self-peel is one of Tristana's most defining features as an ADC, and just like giving a champion's kit more and more goodies until they become powerful is bad design, indiscriminately taking crap away from them until they become weak shouldn't be the default choice of action either.
Find what Tristana needs to be an effective champion with a defined niche, and take away the stuff she has that isn't that. If self-peel is part of her identity as a late game auto attacking hyper carry, then hit stuff like her insane pushing power, grievous wounds or slow that are nice to have, but secondary to her niche as a champion.
Assuming that she needs nerfs, which I'm not convinced of after this latest patch, but whatever.
You can't counterplay it outside of taking Fizz
Christ, it's a verb now?
My least favorite buzz word is breeding, it seems.