html/template is literally nothing more than an "HTML-safe" version of text/template, which is Go's arbitrary text template language. It's meant to be completely a drop-in replacement for text/template, and as such, its design does not give HTML output any special consideration, which an HTML-specific template language would.

I understand the point you're making - I just want to point out that Haml is explicitly designed for HTML, whereas html/template more or less "just happens" to be useful for HTML.

As for ERB, I'm not convinced that it is too different in this regard. I'm not much of a Rubyist, and I find it incredibly frustrating to use, but perhaps that's a matter of personal preference.

{text,html}/template have their warts - I literally started Jetpack because of an unusual html/template quirk I ran into that was tricky to debug. However, I don't think it's any worse than other template language in this regard (my main points of reference are Jinja2, ERB, Haml, and Scribble).

It is context aware, which is actually really awesome! It understands if it is in a tag, in a script, in quotes, in double quotes, in source, in css, in style and lots of stuff I am forgetting and does the custom escaping required to make it safe for that context. That is freaking magical.