This is highly subjective and argumentative. If you think different, please comment!
I love to develop highly interactive and complex apps - that run in the browser. I also think the browser is still the most important tool for accessing them. At least for now. And the next few years. Even on mobile.
Search engines can't find my app's deeper content. That's okay, it's only for members anyway. They still find my
index.html and that's fine enough for indexing.