Isn't losing PGP compatibility a big minus?
That is debatable. If there is a proven better solution, then using something brokendoesn't make sense
I disagree that PGP is "broken". Bad UX? Yes. But it works. Also, if most people use pgp, the network effect is a huge reason to keep using it.
I would disagree with you opinion of it not being broken. It does work, but it has some painful flaws. If people switch to age, the argument could be reversed as far as popularity.