At first blush the fact that all these searches were sent over DNS (which is plain text by default) this was a gross privacy violation. Congress has passed bills allowing ISPs to use your DNS and browsing history and sell it to 3rd parties [1]. With all these searchs being included in DNS queries chrome was basically allowing everyone who wanted that data that you were worried about that mole or that you have that weird fetish.

[1] https://www.nbcnews.com/news/us-news/senate-votes-let-isps-s...

(edit: explaining better what I felt was a privacy violation)