An ‘eyedropper’/‘pipette’ color picker tool would be a very handy addition, I agree 
Looks like it’s been suggested a few times:
- May2015-Color picking for easier building
- Sept2015-Eyedropper in Build Mode
- May2016-Color coding for colorblind people
That last one (May2016) has had it’s main suggestion incorporated recently (giving the colors names; it’s in the dev/latest releases); here’s to hoping the small mention of an eyedropper tool’s still on their radar 