I doubt Go is really a better offer than Java to serve HTML pages. Go promoters are clearly focused on the backend (web APIs).

For instance, my experience with HTML templating in Go using the standard library is that it's really slow. And that's even after taking the pain to optimize them as recommended (caching, etc). But, most of all, each frontend web project in Go has to decide if it's going to reinvent the wheel, or select one of the many short-lived frameworks.

Go w/ templates is more an analog to JSP tech than JSF tech, I think that's the key differentiator. I'm guessing JSP is significantly faster and Go would be more memory efficient, but I hardly doubt any of that matters at the scale these two would be used.

JSF OTTH is a component framework and is much higher level than JSP|go/template. JSF performance probably falls below both JSP and Go templates. But, at a much lower cognitive load that both by an order of magnitude. For instance, to put a street map on a page with PrimeFaces, you simply type:

  <p:gm ::tab-space::

and let the autocomplete in your Java IDE fill in the rest of the characters to form: <p:gmap id="googleMap" apiKey="xyz" />.

Ultimate it's a tradeoff between getting exact control over the HTML (which you often don't need) and developer productivity.

If you're familiar with Go, go for it. But there isn't really a compelling reason for a person or team to switch from Java to Go; Java also has a rich ecosystem of templating engines.

Because we don't miss Java 5.