We are over a year into a pandemic which involved wide-scale lockdowns. Physical key exchange is a nonstarter for broad adoption.
I think the emphasis is on the -ed in involved. That's a temporary condition which is already resolving in much of the world. You may also be overestimating lockdown compliance among average people.
If iMessage had been designed to require a brokerless key exchange, its security would be superior (though in this case, Apple's interception software trumps everything). But iMessage would appear to be less convenient than alternatives like WhatsApp (brokered key exchange, re-keying).
We would be in a much better position right now with email privacy if the version of PGP that doesn't defend from an active attack would have been deployed worldwide.
People who say things like this rarely also want the hassle that comes with it. Key exchanges, re-keying: all a big PITA. But iMessage (and WhatsApp) do key exchanges facilitated by a trusted broker. If you didn't trust the broker, you would have to do more work when making an initial exchange with a peer and more work if they lost their phone/keys.
iMessage has always been a compromise with subtle rough edges. But we trusted Apple because they talked about privacy and made it clear that their business model meant that we should trust them more than competitors. But now, precisely because of how good and effective they secured their devices -- they fear regulation and thought that they could further compromise things and people would go along with it.