To blend colors between each other, digital artists need a low opacity brush, plus painting over, picking the new color, painting again, then picking again... This means picking up the color while preserving the brush's lower opacity multiple times per second. Having the colorpicker pick opacity simply makes this (very common/essential) workflow impossible.
Here's a video of Dave Greco demonstrating a similar workflow: https://youtu.be/-oPp6NE4WL8?t=125
A checkmark to disable picking the opacity would make the software a lot more attractive. It is the main bottleneck for digital artists.
With Autohotkey, I was able to map the color picker to Alt key. When it's pressed, it reads the opacity of the current tool and switches to the color picker. When it's released, it gets back to the previous tool and sets the opacity back to the read value. The experience is not as smooth as I want it to be though.