Job Points

[Alhanelem]

Is there a reason why we can't delevel job points applied like we can for merits

There's no reason to delevel job points. You can get all of them, so there's never a need to get rid of one in order to get different ones. If they did allow it, it wouldn't be refundable since merits aren't, thereby making it more pointless than it already is.
Max out your Pianissamo job points seems like a smarter move than getting rid of 2 of them. Otherwise, use something that will swap your gear faster. either multiple macros or (fight club).