Git is decentralized, but services like Github (and even free ones like Gitlab and Gogs) take away some of this decentralization by having users create an account on them to submit issues and pull requests.

If Gogs implemented email-based issues and pull-requests, nobody would need an account in order to submit them. One would simply send an email containing the issue and/or the pull request to the right address and it would automatically show up in the issue tracker. The author of the issue/PR would be identified as the sender of the email, and all responses will be sent to them via email (as well as show up on Gogs).

The web-based alternative is implementing a federated protocol like StatusNET, but that would require other services to do the same, and it'd be hard since the big ones (Github and Bitbucket) are proprietary.

The email-based approach can be already done manually via git, by the way, and this would be a good compromise between the old way to develop software (email) and the new one (web), and satisfy both camps.