Why does everyone parrot "animation cancelling is unintended/an expoit" as though it's fact? Morello mentioned her ability to animation cancel before she was released and they've known about the ability to animation cancel forever due to the actual unintended nature of flash's interraction with Alistar's Q, and anyone else with a spell that can be cast simply by pressing the button with your cursor out of range.
Riven is based on fighting game mechanics, she has fighting game mechanics, and her animation cancels are not nearly as powerful as people pretend on these boards.
The only change that should be made is that it should be mentioned either in her tooltips or in her champion spotlight.