I'm tempted to compare it to PHP, which exploded in popularity despite (unarguably, IMHO) better languages existing all around it at the time. Go doesn't seem like a bad language in the way that PHP was a bad language for its first 4~5 major versions, but it does find itself surrounded by many more powerful/expressive languages, and is seemingly getting much faster adoption.
I've been learning Go myself, and while I miss some of the features of my normal primary languages (Perl, lately, but also Ruby and Python), I like that I can read other people's Go code without having to look anything up, even though Go is very new to me and I have years experience reading/writing Perl/Ruby/Python. Of course, Perl/Python/Ruby aren't a major paradigm shift away from Go as Haskell is...but, it's still a question of whether it's better to write ten simplistic LOC or two maybe opaque LOC. I tend to prefer concision over verbosity (and thus hate reading Java; I get lost in the trees before I can find the forest).
Maybe Go is a sweet spot for a lot of developers. Rob Pike did a talk called Simplicity is Complicated, about this very subject...I found it a pretty convincing argument. https://www.youtube.com/watch?v=rFejpH_tAHM