See arguments about red-warning unencrypted HTTP and how that pushed the web to update.
Add in that genAI is going to make plausible-looking phishing emails a lot easier for the world to generate en mass, and giving the everyperson something better than "decide if it looks suspicious" is important.
A dead giveaway would otherwise have been that the BIMI issuers are all the now-panicking EV certificate issuers, which nobody will now buy.
