I don't really like Whack/Thwack either, but honestly, I think if an opponent gets hit by those, they deserved the dice roll. Thwack has high startup so it's reactable, and loses to pressure like the rest of Hero's kit, Whack travels incredibly slowly, both spells give the opponent the chance to see the spell in the Command Window ahead of time and stay out of the danger zone, effectively adding to their startup, and if someone is top-decking like a madman then landing a kill with that is pretty much the same thing as a Hail Mary Judge or Green Missile, only those options don't have the possibility of ending your own life instead.
I wouldn't mourn their loss if they were removed in 1v1s, since I pretty much only go for them at kill percent anyway, but I think the RNG really takes a back seat to just how bad those moves are on their own.