I don't think "Sharing is good" is true in the real world. If you apply that as a blanket statement, you'll end up in trouble.
What is legal is not always ethical. I think there's an interesting story there about how Google is legal, if someone doesn't automatically assume it should be just because it is.
The text online isn't always similar to a published text of the past. There is a personal overlap today that changes the rules. Such as this text I'm publishing right now. Forgetting about all the legalities and technicalities, I still feel like it is different than a page published in a book. I still feel like I should have the power to edit or delete it whenever I want in the future, yet Hacker News disagrees and removes my right to modify it, forever capturing it as if it owns it, not me. I still feel like this text is more transitory, where its relevance is mostly right now, and if it were deleted in a month it would be fine, because it's mostly just chit chat.
Certainly we could live in a world where everyone has microphones transcribing everything they ever say, which is transmitted to Google, and provided to researchers, where all kinds of uses could emerge. But that's a different world than the one where we've developed rules for today. Right now, I feel like most things I say are in passing, and should not only disappear, but won't spread where someone is capturing and propagating it beyond my control.
What control do I have over my text that is in this Common Crawler database? What if it captured information that was considered to be ephemeral in the website's context, and ripped it out of its home where it's now part of this collective publication, where anyone can use it for anything?
Sharing could be good in a world where people are not selfish and malicious. But in this one, many people will use whatever data they can get their hands on for selfish and malicious purposes, that do not benefit you, the author, in any way. I bet a large percentage of use for that Common Crawler database was harmful to society, such as for helping spammers generate fake content.