Last time I used a language without generics I had to cast web form values (we used a library with a general-purpose representation of "form control backed by object"). Sometimes these were incorrect, and had to be debugged. More than that, when working on the form code I had to constantly keep track of the types of things in my head, because there was no way to have the computer do it for me (we did try Hungarian notation for a bit but that was a disaster). Is it the end of the world? No. Does it slow development? Absolutely.

In JavaScript, none at all.. ;-)

In C#, before generics, wiring up a typed collection/enumerable was seriously painful.

I think the right way to think about that is: "what solutions has lack of generics prevented me from writing?". From the expressive end of the power continuum, Go is way down there (somewhere below Blub probably).

http://www.paulgraham.com/avg.html