Disappointed to learn that the new colour picker is not HEX but is actually an HSV colour picker, why not just make it an RGB colour picker & it would be brilliant if we could type in the values after converting RGB to HSV.
This could really help in some cases when we want to use the same colors repeatedly. Another feature could be a dropper or a method to save/favourite colors for easy access and control.
Colour in UE4 isn't 0-255 but 0-1 (and beyond 1), so isn't directly compatible with hex values which is why they probably don't let you. However it isn't hard at all the convert them so there's no reason not to, even the built-in picker lets you use them. I think HSV is easier to understand for the general public though. It's what most colour pickers in racing games use.