Can Akali's level 6 all in be given more counterplay for casters?
Assassins' baseline all ins shouldn't be unconditional and unavoidable.
With every other assassin, some condition has to be met before they can kill you, which provides counterplay. Zed has to bring your health down a bit before he can ult you. Katarina's daggers can be played around. Talon has to manage to get in close to you.
Akali has no condition. She can just ult on you at any time if you attempt to auto a minion and her Ignite is up. Casters don't have enough health or resistance to survive it.