Are Max CDR Summoner Spells underrated?

Earlier today I wanted to try something new on my support build to see how it would go so I decided to get max CDR on my summoner spells just to see how useful it really is. It seemed to work wonderful and honestly I didn't see any downside to doing it other than getting the extra 450g on my ionian boots for distortion early on. The only reason I think I haven't seen this done is because I don't think anyone known has ever done it so it isn't "Meta".

Here's my build I used and the stats for it (tested on Braum):

+ Insight Mastery = 40% CDR on Ghost, Flash, and Teleport.

Brings Flash down to a 3 min cooldown from a 5 min cooldown

Brings Ghost down to 126 secs from 210 secs cooldown.

Buffs BOTH Ghost and Flash:

Ghost increases movement speed by 40% instead of 27% for 10 secs.

Flash gains 20% movement speed for 1 second after flashing.

The pros just seem too good. I mean ghost and flash can both be used offensively and defensively. The upgraded ghost seems to be amazing when you know when your jungle is about to help gank bottom to get close enough in time to land a good cc. The cooldown is so low on ghost alone the likely hood when using it defensively is that it will probably be back up by the time you're in trouble again.