Why did Riot even make Cleanse as a Summoner Spell?

I mean, Cleanse hasn't had many, if any, changes in the time it's been a part of League. I don't understand why this spell is even around when they decided to put QSS in the game (pre- can't cleanse WW or Zed ult).

This spell deserves to see play when an enemy comp has a lot of CC and you need to survive.

My thoughts on changing Cleanse:

Current Cleanse:

Removes all disables (excluding Suppression) and summoner spells debuffs affecting your champion and grants 65% crowd control reduction for 3 seconds.

Cooldown: 210 seconds (3.5 minutes)

Updated Cleanse:

Upon activation, this summoner spell will remove all disables (including Suppression) and summoner spell debuffs affecting your champion. For the next 3 seconds the summoned champion is granted 65% disable reduction and 50 armor and magic resist. edit: The bonus resist could be changed to a level scaling damage reduction. 10/15/20% at 1/6/11.

Cooldown: 180 seconds (3 minutes).

Edit: I understand why Riot removed the Supression from it, but what i don't get is that they did that before they removed it from QSS.

Cleanse is a SUMMONER spell. It deserves to be more powerful than an item you buy in-game. Before Heal become a solid pick for ADCs, there is literally nothing they take now.

Another version of Cleanse could be:

When activated, Cleanse will prevent all disables for 1.5 seconds. After 1.5 second has passed, all disables affecting this champion are reduced by 50% for 3 seconds.

Cooldown: 210-180 seconds.