@1script - yes, that's the way I understood it as well. We noindexed millions of pages which were not necessary. For example we have ~2 million photos uploaded and each naturally had its own page. Most of these are now noindexed apart from ~20,000 which have been manually featured over the years. Similar story with our forum - we noindexed all threads that had less than 2 replies. We cut down the number of pages in the index from several million to a few hundred thousand. Maybe we need to cut even more for it to have a positive effect. Because so far the only effect has been even worse rankings than before. I am very wary of noindexing much more, because of the deleterious effects so far.
I think we may need to be careful to only noindex pages if they don't have any valuable inbound links. This means running lots of reports through SEO tools to really understand the thousands of inbound links we have and ensure they aren't lost to 404'd pages and so on. Yes, it's doing things only for SEO, but really this is what the outcome is of Google's changes of the past 2 years. Focussing just on your content / features, etc. does not work anymore.