Data types aren't the bottleneck, the deployment model is. Editing a Go application requires the following steps:

  1.  Edit the project's files.
  2.  Open the (scary and alienating) command line.
  3.  Run `go build` and hope it works right.
  4.  Find and stop the old running server process and start the new version

Oh, and you'd better hope step 3 goes smoothly, because a tiny mistake anywhere in your application will cause this weird thing called a "compiler error" that means that the entire thing will break. Editing a Wordpress site, on the other hand, looks like this:

  1.  Edit the project's files.
  2.  There is no step 2.

As developers, we're comfortable with the first workflow. We happily accept the added complexity because of all the other nice things it gives us and because we're probably using other tools like version control that end up making our experience much more uniform between the two. But to a user whose primary experience is with editing Word documents there is a huge jump there.