PGP isn't exactly known for being user friendly. Gmail does not support it out of the box. The average person just can't be expected to understand that kind of cryptography.
That said, if you encrypt the device, encrypt the transport method, and the receiving device, that's pretty damn secure in about 98% of situations. WhatsApp just rolled out end to end encryption for their service as well, and they only charge a dollar a year (I think). That's encryption the average person can use. When an 18 year old mother of two in Sao Paulo can review her grocery list with her mother via secure encryption and neither of them know they're even doing it, that's a whole new level of secure. Compare that to the plain text emails I get from my boss about what I might consider vastly more important things at the office.
The golden era of unencrypted plaintext email is just about dead, I think, is the problem for intelligence agencies. At least for those people outside of gleaming glass corporate offices.