will Master Scopes get its own UI button?

In 2.8 master scopes had its own tab so it was very fast to switch between Master Scope and Master Spectrum witch is especially use full when looping samples.

Currently you have to access master scopes from a dropdown menu

I was looking for that too, I think it needs its own UI button too.

For fine-tuning loops? Why not use the sample editor and zoom in for visual feedback?

Because i can see the loop better using the master scope as it visually shows me the loop pattern in real time. as the sample is playing i can see the peaks and the point at which the sample repeats. And when i am sampling a vst i can see how the long the loop will be before i set the sample length before capture.