You picked a bad time to complain about this, because a whole bunch of Pi 400s have been popping up in stock over the past few days.
rpilocator doesn't track the 400, but they do tweet when they see them in stock: https://twitter.com/rpilocator
As for "why not" the alternatives, it's because they get no ongoing support, and don't run mainline Linux, so you're stuck with what they ship with, and can never update them.
You picked a bad time to complain about this, because a whole bunch of Pi 400s have been popping up in stock over the past few days.
rpilocator doesn't track the 400, but they do tweet when they see them in stock: https://twitter.com/rpilocator
As for "why not" the alternatives, it's because they get no ongoing support, and don't run mainline Linux, so you're stuck with what they ship with, and can never update them.