CDR being way too common is definitely something bad for the game's health

About half of the whole item roster presently in the game on classic SR has CDR attached to it. This has the effect of increasing the damage output of a lot of champions relying on ability casts to deal or greatly enhance their damage such as and many others (I only mentioned these because they are kinda popular amongst complains lately). In a meta where damage is already way over the board, we don't need that much CDR in items nor do we need CDR steroids such as 's ult interaction with Q and upcoming ult interaction with Q. Trading with champions was previously done by exploiting the opponent's cooldowns but now, everything is so fast that you barely have the time to do anything and even for those few champions with long cooldowns, the itemisation has leaned so much in favor of CDR that we can't even recognise the old item system who gave CDR only on certain utility items for mages and some tanks.

Some cooldown reduction has to go, or else an array of an ever increasing number of champions will just become more and more difficult to balance.