Why do 3/4 AD assassins get ranged wave clear?

For roaming.

so that they can exist in lane and so that khazix can actually take the raptor camp

has to get close for his W which is his only AoE on his base spells, doesn't have good waveclear and waveclear is tied to his W on a 22 sec CD.

I don't see why they shouldn't, if they didn't have waveclear, they'd be at the mercy of mages.

Also, Kha has waveclear? This is a genuine question, because his jump and the small explosion on spikes doesn't really seem that great.

Mages also have waveclear, but they can AA farm at the cost of mobility which is a really good tradeoff.

Syndra can pretty much oneshot waves at level 5, and most mages are best off just pushing people in. Kha'Zix's W isn't all that good and he can't really oneshot waves without hydra

Talon W doesn't oneshot casters before rank 4-5'ish.

Zed has to use his whole combo on waveclearing