Google continues to make more bad choices in its quest for alleviating its advertisers whining about the nature of the internet? Not sure, their rationale doesn't really make sense here. Just looked it up and apparently it's to make pictures "harder to steal". So basically just purposefully infuriating people that use Google Images by forcing them to right click -> copy image address.
I swear Google keeps removing functionality for really dumb reasons. Reminds me of when YouTube removed your ability to create folders to organize your subscribed channels into.