Name a champion who doesn't benefit hugely from 40% cdr

Yasuo and Rumble. They're already manaless and have super low CDs on all but one of their abilities.

Everyone obviously does... now is it optimal to get?

Tryndamere.

Q can be kept up near-permanently while catching axes. W is refreshed by catching axes.

Akali.

Ryze, he gets like 30% CDR free from his kit, right?

And pretty much every hypercarry ADC.

because her Q is set to 2 second cd, not reduced to 2 second cd.

Jace, the Mind Sculptor

one's that come to mind

Idk man, seems everyone could benefit with a 1/2 cooldown ulti, utility or escape. Teemo LOVES it. Twice as many shrooms? Twice as much trollig.

Tryndamere loves 40% CDR. If he's AP. :P

some adcs mainly.

I would say Lee, WW, Trundle, and Udyr all have low enough cooldowns to do whatever they please. Lee, WW, and Trundle obviously get their ults more often, but it's not like they'll be rattling off ults every teamfight either.

The bigger question is is it worth it on said champions? Everyone benefits from CDR, but only a small % actually want to build CDR, rest it is actually bad on.

Like Jax is the first to come to mind. Why would he waste his time building CDR when he wants to build a lot of damage and maybe some tankiness and its off the normal path? At most he would get Black Cleaver and thats it.

now that his energy costs are hilariously ludicrous

<- If you mean from items.