I don't know exactly what the problem is for Go. There are tradeoffs, e.g., just with the type system: impredicative, stratified or predicative quantification, implicit subtyping or explicit type instantiation, value restrictions, variance handling for mutable inductive types, Hindley-Milner or bidirectional typechecking, etc. There are more tradeoffs with the implementation. Fortunately, these are all well understood by now.
However, it is also true that many mainstream languages famously got generics wrong. What's most infurating about this situation is that a lot of research just gets ignored. If the question is really "should Go have generics whose design is based on C++ templates and/or Java generics" then the only sane answer is a resounding no.