Any examples? Perhaps you mean either Generics or the module system (the two elephants in the rather large and accommodating room)? I read almost all proposals for Generics, and, perhaps to my inexperienced eyes, the problem seems hard. The ramifications on the language design are not trivial, and the benefits, again, from my quite limited world view, are not so easy to quantify, otherwise how can one justify the extreme productivity spawned by the language? In the cloud business no less.
I have almost no stake in this, I don't even use the language professionally, but I find the supposed criticism a bit over the top. I'd wager that an example implementation of Generics that fits nicely with the language and works for a big and healthy code base would absolutely not go unnoticed by Russ and the other core members, but we have to accept that it is not easy.