For me it raises the question of weather it works with programs written in anything other than GO. My first thoughts were - hey I'm learning Rust and Flutter looks neat, will this allow me to use Flutter as a GUI for my rust apps? They say it's written in GO, so that must be relevant right? And it probably means it's meant for apps written in GO right?

It's an interesting line. I like the notion of apps I use being written in one of the more modern languages (GO or Rust) but it's not a core feature to a user. This means I can appreciate the language being mentioned but in a much less prominent way. If language isn't critical to a user or developer (of other things) IMO it shouldn't be so prominently mentioned.