Why isn't Riven allowed to Q towards cursor?

funny thing is, there is a special case where she is:

if you have an enemy in range, and you mouse over them. then you do it in place, on the enemy

It's a relic from back when she was initially designed and Riven's fanbase is so rabid that Riot can't even make QoL changes to her. No other dash works like that anymore except for Rivens but they just refuse to change it.

Quickcast

because that would make her even easier to play