I'm honestly not sure. When I first started out, all the applications I used had been built five years prior. We made small tweaks and continued to use them because they just worked

Now? I think newer technologies come out faster and capture people's attention. They want to use the new shiny thing. I think the "business people" want to have a big budget project to get recognition within large orgs. I think developers want to use the latest and coolest stuff. I think people feel like we already live in a disposable culture, why would our sites and apps be any different? You combine all of these and suddenly the pressure and inertia not to move or rebuild or redesign regularly is too much to overcome.

I still remember going to a ReactJS class and the guy running it kept saying, "Don't get me wrong, BackboneJS is still a hell of a library and is still relevant and awesome to build stuff with BUT React does a few things better."

This is where we are. Huge financial investments, time and energy to get a 3-5% bump in efficiency? Doesn't make sense to me.