If your PGP key isn't signed by anyone, then there's no way to verify that it's really you - other than contacting you and checking the fingerprint. By having a trusted third party such as Governikus sign it, anyone can verify instantly that _this_ PGP key is actually from a person with a _name_ for which they also have a government ID with that exact name.

I can envision a _lot_ of use cases for having your name publicly recognized by a trusted party.