Go feels under-engineered because it only solves real problems. If you've ever worked in a wood shop, you've probably made a jig at some point.
They often solve hyper-specific problems and work only with your specific tools. And when you look at ones that have been used a lot, they sometimes seem a little weird.
And when you compare them to “real” tools, “general” tools like you'd buy from a catalog, they're pretty homey or homely depending on how you're thinking about it.