Why is there a level meter on folder track headers which has never worked? As I am finding out in this project, when all folders are closed it would be very useful to have this - omission? - rectified. 
I’ve never noticed this. Now I’ll have to look for it.
After two years of using Cubase Pro I’m finding that the better I get at using it, the more I notice functions and features that – break down and stop working, do not work as promised in the Operations Manual or are insufficiently detailed in the Manual and support documentation. Without the forums and the other users, I’d be totally lost.
Thought never crossed my mind actually. Logic Pro has folder busses which in effect makes the folder a group bus, and they have meters that are visible. It might be a bit confusing to see meters on a Cubase track folder when the folder itself is not generating any audio. But I see your point, it would be a neat feature. But I’d rather Cubase get Logic’s folder bus feature which would take the feature to its… _logic_al conclusion.
But what should it display ? The loudest source ? The sum, even though there is no summing going on.
Folders have no output and should not display any, that would just be confusing.
If folders and groups where somehow able to be used together then they absolutely should.
A sum would be fine. Just to show that something is going on. I don’t think I’d find it confusing. That folder buss idea might be worth a look, though I’m not clear on what the advantage would be…