Maybe Chrome would be up for it at some point in the future as HTTP form submissions become rarer, though I don't know how they made this decision.

Edit: Amusingly, even though I normally use Firefox, I haven't noticed this UI element recently because I'm so conscious of HTTPS—working on Let's Encrypt and support for it—that I rarely even try to enter information into a non-HTTPS site in the first place. :-) (so I might not be quite the target audience for this notification)