I don't think Go's developers are aware of "most" research in PL design. But that's true of most languages, really, there are a billion papers to read. I think people are frustrated by what research they chose to ignore, though... anyway, saying that OCaml and C++ are the only major languages to support structural typing is a bit silly, since a lot of other languages that are probably more popular than OCaml have it (like F# and Scala). And Go's variant of structural typing is pretty limited.