I am mostly for the ostensible cleaning up of YouTube comments, but what got me was that any time you share a YouTube video on Google+ proper or comment in a thread where someone shared a YouTube video, it automatically cross-posts what you said back to the comments underneath the video on YouTube. And that's not just for shares/comments going forward: it's everything you've ever shared publicly, ever. I'm now gettin…
If you'd re-shared someone elses video share, you're SOL. I deleted a few of those posts, re-posted others as URL links to the original (this loses comments, if any).
It used to be you could identify your YT comments from within YT. I've got slightly separated accounts on G+ and YT, and the comments originating from G+ don't seem to show under the YT account. I'm not sure there's any clean way to get rid of them.
I pretty much share your view of where my comments get posted -- I place them in a context, and that's where I intend for them to remain. The YT thing was (yet another) huge trust violation. Especially given that comment management tools are so pissedly poor on G+.