This attitude drives me all sorts of nuts. Everybody with any familiarity with PGP that has ever thought about integrating it as a tool in a broader system always gets hung up on the notion that they don't want to invest their personal public keys in some library. "Give my public keys to the browser? Crazy!"
These people don't get it. The value of libgpg isn't that it makes it easier to build apps on your personal public keys. It's that it allows you to build applications that use crypto without reinventing an entire crypto stack. The products that used libgpg would be generating their own keys, often ephemerally.
This attitude has resulted in untold hundreds of shipping software products with trivially exploitable crypto flaws that were resolved by PGP's designers in the 1990s. It has been a massive net loss for information security.
It would be incredibly useful to have such a Zlib-caliber GPG library.