The issue is that the 25-29 generation is terrible for the United States and that period was terrible developmentally. They redid the developmental structure, but it takes time. That required a reliance on young players (Pulisic, Wood, Arriola, Yedlin) or old players (Bradley, Dempsey, the defense/goalies). That's not what you want. The upside for USA? The young players are good. Pulisic can be a star. Miazga/Brooks/CCV/EPB should provide at least two high quality CBs. Yedlin is really starting to develop. Wood is a decent striker. Horvath/Gonzalez are solid keepers. There are a ton of other young players starting to show up in Europe (Sargent, McKennie, Gooch, Perez, Hyndman, Zelalem, Wright, Weah). The future, even given this hiccup, is bright.
With regards to diversity, I don't think that's a fair comment. There's a lot of diversity in the system both at the senior level and throughout the youth ranks.