Support itemization is too powerful
I am of the opinion that support itemization is currently too powerful, and the power creep of supports has had numerous negative ripples throughout the rest of the game.
It's no secret that support is the least popular role. In an effort to remedy this, Riot not only buffed support champion numbers, but released a bevy of new and powerful items to try and make the role a little more attractive to other players. Now, though Riot hasn't given us actual statistics about the popularity of support compared to other roles - they've already admitted in blog posts that support remains the least popular position.
The new support items did nothing to address the relative undesirability of the support role...but they've also negatively warped much of the rest of the game as well.
*** ADC's doing too much damage**
There have been numerous complaints about ADCs feeling like ranged assassins because of their ability to pump out overly high amounts of damage. But a good bit of the problem here is that items like Redemption, Ardent, Locket, etc are simply overtuned. They overly augment support players' already good utility, and make it too difficult to kill ADCs. ADC damage would feel alot more balanced if assassins and divers were able to more reliably kill the carry.
*** Game feeling like it's decided by the better bot lane**
Bot lane has always been important. Winning bot means getting two players ahead instead of one, it means dragon control, and usually makes it easier to get the first tower. But with supports being so powerful now, it's led to the bot lane snowball being that much stronger. Depending upon the support, and their gold income, sometimes they are able to actually duel carries. It's disheartening to see the enemy Kench support assassinate my top or mid.
*** Massive shields are not fun to deal with**
League was never meant to have overly high shield values. The game's designers realized that shields aren't fun to deal with. They purposely kept the actual values of shields low - and compensated by adding utility to the shields instead. That's why Janna's shield adds AD, while Lulu gives attack speed. Even locket had a low shield value, because it was compensated by the item's aura. Somewhere along the way, the gams's current designers lost sight of this value. Now, if the item itself doesn't provide a shield, it provides a large amount of AP to buff the support's built in shields instead.
Ardent shouldn't give its users 60 AP, Shurelya's doesn't need to give 40 AP. Based upon the old design values, giving supports the ability to cast a massive AoE heal _after death_ (Redemption) is obscene.
**tl;dr: **
Support itemization was overly buffed to try and make the role more popular - the effort was a failure. Now supports are too powerful and making the game worse for everyone. As such, support items should be nerfed.