Java is the obvious example that springs to mind. Because of the requirement to be backwards compatible with Java 1.4, all the type information is erased during compilation. The call for reified types in Java has been heard for over a decade now.

C++ compile type templating is the cause of egregiously long compilation speeds. One of the original drivers for the creation of Go was the speed of C++ compilation.

I don't think you can separate a desire that generics was implemented a different way in these examples from the regret that their current implementation causes.