I would like CDR to be retooled into 'Spell Haste'

That is to say, the stat we build would increase the rate at which cooldowns recharge. I am honestly tired of building a major CDR item like Morello's after having used a long cooldown ult in a not so recent teamfight, and the amount of effective delay between my ult usage and availability is virtually 0 benefit, making the CDR useless for this period. I would instead like a system where I can haste the remaining cooldown through the stat. It'd be just like attack speed but for spells.

Currently, if I use a Karthus ult for a teamfight with 180 second cooldown and then buy Morello's, it doesn't do anything for the currently delay. If I had +25% spell haste, then I would be reducing the remaining cooldown by 20% as soon as I got the item.

The second reason is because CDR scales hyperbolically with DPS. This isn't that important for burst mages, but for mages that constantly press buttons, 10% CDR at 0% is much less effective than 10% at 30%. Even if your ultimate has a long cooldown, if you use it off cooldown regularly, the amount of ults usable in a game spike up dramatically the more CDR you have.

The third reason is simply more room for stat budget. Currently, 10% the best allocation for an item. If you get 20%, it can be difficult to work in other items. 5% from runes will not work for getting the cap. 15% was absolutely awful on boots. By changing it to Spell Haste, 40 CDR is achieved through ~65% spell haste. 45% CDR is achieved through ~80% spell haste. This method allows the stat to be sprinkled in small amounts over a large amount of items without all being just 10%. It could also allow better design room for cooldown slowing mechanics, but that's just me spitballing. More importantly, it could allow for utility buffs that increase spell haste above the cap.