This is pretty much my thoughts on it too..
Before we got OOS ported it was a horrible situation jumping to custom ROMs, realising you're missing features then jumping back..
..I tried every single camera app out there.. none of them match up in regards to video and slow motion doesn't exist on any of them..
It's only annoying if you ever need it I suppose but when you do it'll stick with you.
But yea just having an option would be brilliant on any ROM tbh