Build diversity is what makes the game fun. Please don't take it away
Currently, every adc and their mom builds
, and either lifesteal (
or
, or armour pen. The only exception being
who swaps out his
for a
and
who is agruably more of an APC than an ADC. It's boring and unfun to build the same items every game.
Take someone like
who has quite a few different build paths. An enchanter path, such as
, a tank path, such as
, or he can mix both as needed. Another good example of someone with build diversity is
(
all being viable options).
It's a lot more fun playing a champ where you have to think about the best build for the current situation, instead of playing
and building
99% of games. It's also less fun to see someone playing
and knowing they'll build the good ol' 
again.
Please don't kill build diversity. It's more fun when a champion, or a class as a whole, can build situationally instead of the same copy-paste 6 item build every game because either 1. that build is way stronger in every situation than the others or 2. all of the other items for that class are way weaker in comparison.