I Don't Think the Assassin Meta is the Problem
Don't get me wrong, I'm sick of seeing assassins run around insta-killing people, but I don't think the meta is causing the game to be unfun.
There were assassin metas in the past (part of S3 and S4) and these metas were nowhere near as crazy as this one.
I personally think that the game is unfun due to the gradual changes made to the core game. The changes to runes, masteries, global and passive gold, items, the jungle (rift scuttler), etc. have really changed the flow of the game. In my opinion these changes have made the game worse.
were dominating both top and mid lel
more often to handle assassins better.
and company do their job better.