Shock, horror.! I know; hate to disagree with Greg (because he rocks.!) but on this one, for me, he misses the point when discussing this feature with the devs at Hamburg.
He’s right that individual plugins will always offer more detail. However, its really helpful and quick and useful to be able to have an overview of compression levels across several (all) channels at once - just by glancing at the Gain Reduction meters in the channel meters, as I do in Studio One. Sometimes you can quickly spot where issues are; sometimes, you just got to go in and pull all compression levels back a bit… 
But hey, I’m just saying, they help me on occasion.
puma
[an old post/Feature Request thread of mine - GR meters in MixConsole Channel (like StudioOne) - Cubase - Steinberg Forums]