Ultra-short combo is the problem.

Ultra-short combo make the game less fun.

Reason these champs are problematic:

• They give macros/bots user an advantage who can just press one button to pull the entire combo in 0.25s. Not by coincident Kat and Riven are the most bot-ed champions.
• They provide little counter-play when their combo is un-interruptable. Nothing can be done once they start it.
• They make having low pings a make-or-break element.

I'd suggest adding a 0.25s "global" cooldown after using 2 abilities consecutively, during which they cannot use another ability. Any champ that Riot deems has been adversely affected by the change would receive compensation in ratio or raw dmg.

Please share your thought.