Shouldn't we have it too?
The feature itself isn't new—it's just more obvious now. I'm happy to add it for Chemistry if it's likely to be used. The one caveat I have is that chemistry.stackexchange.com is not often cited in academic papers (cf. MathOverflow). Obviously, there could be a chicken and egg problem here: we don't have a citation link, so nobody cites the site.
A significant cost of adding the feature is a new menu item under every post. That's hardly a problem if y'all use the link. But it's a waste of cognitive space if the feature isn't used much. So if the community would like to have citations, I'd appreciate someone helping me find examples of Chemistry—Stack Exchange being used as a reference in academic settings. That way, I can be confident that turning on the citation feature will meet an actual need.