I main the item Tear and my thoughts on the Tear changes
Yes, I do main tear. Yes, you can main an item - because I build it on 90% of my champion roster. Some people get attached to champions, well, I get attached to items - so deal with it. Don't believe me then check my match history. This is how I use the item:
High CDR / High Mana =
-You will be using more abilities, but get less out of those abilities; which means you will need to perform better than average against your opponents. -Because your abilities will deal less damage than if you didn't buy tear, you will be using more mana than before to waveclear and kill opponents. -You will deal a lot more damage than somebody who didn't build into a tear item at mid / late game. -I sacrifice damage runes and global power by going CDR runes -Hold lanes and offer extreme sustain to team due to an impossible to use resource; never go OOM and have more choices than if you had to resource manage
These are the current changes: LESS QQ Can gain up to two stacks every 8 seconds ⇒ Can gain up to three stacks every 12 seconds
This change is backwards, it should be the other way around. You should get the ability to stack quicker with more charges to use as well. The current changes are benefiting champions that utilize the tear less than champions who actually do poke often.
These champions are good for tear but are being nerfed with tear changes:

These champions are not so good for tear but are being buffed for tear changes:

Why is it that we're buffing champions that don't even need a tear to begin with, they don't poke or do anything like that - they literally all either blow up their combo at once or just so happen to have a 3 combo ability that has a longer CDR. Champions with higher CDR will receive this as a buff as compared to champions that actually need mana to spam will receive this as a nerf.
My recommended change for tear to be ever considered a viable option:
=
+400 mana = 0 Mana
+120 ability power
UNIQUE: 0% cooldown reduction
UNIQUE: Killing an enemy minion refunds 3% of your missing mana
Can now stack up to 6 charges one time, while recovering a charge every 3 seconds. (Most poke champions will be able to use a spam ability every 3 seconds.) Stacking will remain the same.
No longer gives AD based on mana, however will now deal 8% of your enemy life points per auto attack, enemy champions hits will have 10% of their mana pool removed based on missing mana when at full build.
Now gives: 80 AP / 20 CDR and a new UNIQUE passive. UNIQUE PASSIVE: Enemy champions hit with this ability will have 25% of their mana pool removed based on maximum mana; suffering the amount of mana lost as physical damage.
or
you have 2 free item slots to build cdr(
mandatory at full build). Mages need atleast 1 item with 20% cdr available.