Filippo Valsorda wrote an exellent essay on why he's giving up on PGP. I have long believed PGP to be more trouble than it is worth. It's hard to use correctly, and easy to get wrong. More generally, e-mail is inherently difficult to secure because of all the different things we ask of it and use it for.
Valsorda has a different complaint, that its long-term secrets are an unnecessary source of risk:
But the real issues, I realized, are more subtle. I never felt confident in the security of my long-term keys. The more time passed, the more I would feel uneasy about any specific key. Yubikeys would get exposed to hotel rooms. Offline keys would sit in a far away drawer or safe. Vulnerabilities would be announced. USB devices would get plugged in.
A long-term key is as secure as the minimum common denominator of your security practices over its lifetime. It's the weak link.
Worse, long-term key patterns, like collecting signatures and printing fingerprints on business cards, discourage practices that would otherwise be obvious hygiene: rotating keys often, having different keys for different devices, compartmentalization. Such practices actually encourage expanding the attack surface by making backups of the key.
Both he and I favor encrypted messaging, either Signal or OTR.