Cass' Q isn't targeted, it's a delayed groun AE, exactly the same as Karthus.
I would actually prefer they just treat all abilities equally. I don't use range indicators, as I said (because no matter what anyone says, there IS a delay), but I have dumb cast bound to shift + QWER, so that's how I would like to 'aim' Yasuo's Q. I understand their reasoning in making those 3 abilities all smart cast by default, but disabling people from using them differently is ass backwards.
Edit: Although I would say with less than 10 games played of Yasuo, I already am within a couple units of range of knowing when my Q will hit or not. I don't actually miss the range indicator on it as much as I thought I would. The whirlwind is just a line, the range I'm less sure on but it goes so far I usually know if it'll hit or if it's in the 'maybe' range. Otherwise I just treat it like every other skillshot and use my mouse cursor as my crosshair.