Your observation that it's possible to build xyz type of websites does not adequately discount the necessity of such features.
I'm talking about improving those lightweight and beautiful websites even further. I implement some of those features on every project, to deliver the maximum content & experience quality in every network and device condition possible.
You can't seriously try to shoe-horn the entire platform into whatever your vision of beauty is. Please keep an open mind about a complex future medium, that can effectively accommodate Netflix, YouTube, Facebook, Wikipedia, Photoshop, Open Office, Google Maps, Skype, Auto CAD, Grand Theft Auto VR, ...