its only appeal is relatively minor
Is that factual, or also something you feel like?
To us simple folks, you know, it looks as if Caddy has a number of use cases where it's a much neater fit than nginx. We like the extreme simplicity and the transparency of it all. Some of us also like the Go it's written in. What with the magic Go modularity, you can actually embed this server in your web-app. Or is it the other way round? Comes in handy, at any rate.