The thing is, it's a strawman, because an ordinary https-certificate, even one that's signed by a CA, is *also* not considered good enough for a bank, and infact, atleast where I live (Norway) I'm fairly sure no bank goes without extended validation or whatever it's named.
That causes significant and clear gui-changes, namely a large green bar stating the name of the institution.
In contrast, https causes a tiny grey padlock to appear in the bottom-right corner, next to the Sync-icon, which is pretty close to totally nonvisible.
Yes, I get the point that https:-self-signed has an identical url to https:-with-certificate and that thus users with bookmarks is at risk. (few users enter the url with https: Joe Public has by this time LONG gotten used to not typing http(s):// instead if they enter the address at all, they go for "www.mybank.com". That often redirects to https://www.mybank.com/ but I don't think a large fraction of users would notice if it stopped doing that.
AND - and that's my most significant point: The question isn't if a change would cause harm. The question is if the benefits would outweigh the harm, or vice versa. One practical consequence of the current situation, is that self-signed, is essentially not-usable. And encryption of any sort whatsoever is, essentially, not available for everyone hosting a simple website on a shared-ip-address which means probably 95% of the websites in the world.
The practical result of this decision, despite being made for reasons of security -- is that nearly all websites have no encryption whatsoever.