I've deindexed 90% of site pages, all user profiles. Will this hurt the site’s ranking as a Whole

We are running a quiz, stories, polls, questions website. The website has a total nearly 1M pages. Most of them (930K) are user profile pages, and related pages for the users ("About Me", "Stuff", "Followers", "Activity").

Only ~70K pages of the website contains quizzes, stories, polls, questions. These pages have much higher quality and more content comparing to the user profile pages.

The user profiles and related pages have a relative "thin" content, and while reading a lot of forums & discussions, I decided to follow the "global advice" and I've "noindex, follow" them, to avoid potential penalty from Google and to increase my overall website and remaining pages ranking


Just after doing this, 3 months ago, I observed a ~20% traffic drop from Google organic, that persisted even now. The 20% drop, is caused mainly, according to the Google Analytics, by the quiz, stories, questions page, which I consider strange


My questions:
1) Do you think that I've done correctly? From this huge "noidex, follow" action I do not see any benefit till now, just the ~20% traffic drop. Also, I am afraid to remove the "noindex, follow" tag added to the user profiles, because of possible google penalties for thin content.

2) Do you think the Google will recalculate the overall ranking of my website better in future, because of this, and the organic traffic will raise recover?


Thank you in advance.