The problem I see with the game as a whole is the structure of class roles.
Assassins beat mages and ADCs (until a few items)
Burst mages kill ADCs (until crit/lifesteal)
Tanks beat mages because they live through the burst and do sustained.
ADCs beat tanks because crits have no CDs
ADCs beat mages because crits do more than spells.
ADCs beat assassins because of crit + lifesteal
Notice a trend? ADCs at 6 items beat everyone and everything because of how damage/crit/attackspeed scale together, and lifesteal makes them durable as a result. It means they never have to think about their item choices. It's always just get a nice mix of all three stats, because it shits on everyone.
The beauty of Rock Paper Scissors, is that they each beat each other, and lose to the other.
Why not try to have League a similar way?
Assassins/Mages > ADCs > Tanks > Assassins/Mages
If crit was focused more on dealing a % of the target's health, it would stop marksmen from two shotting everything squishy while destroying tanks. They'd have to pick between excelling at one, or being mediocre at both.
That way, if you wanted to focus on killing tanks, you'd build AS/Crit and shred them, but struggle to kill squishier targets.
If you were more concerned about the enemy ADC or mage, you'd focus on AS/Damage.
Botrk currently deals 8% of the targets max health as bonus physical. Assume its a 4k health target, you're only doing 320 extra. 210 AD gives the same amount when critting, except it will do the same to everyone, not just tanks.
It would also give mages a purpose in the game, other than "Make your ADC do more damage by forcing the enemy tanks to build MR" like they currently are.