Earlier quoted context omitted.
Why stick with GnuPG? I'm also interested in trying to understand why use age instead of GnuPG?
The main argument in favour of age is that it only does one thing: encrypting files, and does it 'well' in the sense there is no need to edit your gnupg config file to exclude all the crypto from the 90s that your version of gnupg might decide to default to. This makes things significantly simpler in terms of the code for age, which reduces the possible bugs and possible misuse. GnuPG is more versatile and tries to s…
Well, on "written in Go" part, I remember looking at the crypto code 2-3 years ago (??), and it was full of unnecessary copies. You know the practice of using explicit_bzero, avoiding copying, and so forth? In this case neither I remember was being the followed practice (it uses GC anyways), in fact, I remember copying like no tomorrow. Correct me if I am wrong though. Regardless, languages with GC are usually a no-no. There is a chapter on it in "Cryptography Engineering: Design Principles and Practical Applications by by Bruce Schneier, Niels Ferguson, and Tadayoshi Kohno", the name of the chapter is: "Implementation Issues". It mentions Java (as not being a good language for crypto due to GC), and I think C as well.
In any case, it has been a while, and I am currently tired. Feel free to correct me, of course.