[daigoba66]

To your point, I would also love to see more improvement in the area of using HTML/CSS/JS as a proper user interface toolkit. For example, Flexbox and CSS Grid Layout are steps in the right direction.

The web browser is a powerful sandboxed VM installed on virtually all Internet connected devices. And yet we a terrible toolkit for building applications on top of this VM (and I know it's because existing tools were built for hyperlinked documents and not proper stateful applications).

Also an interesting interesting topic are the different classes of these Internet applications. On one hand you have applications like Gmail, which are intended to reach a broad audience and should work on most "platforms" (substitute "web browser" for "platform" in this case). But you also have the traditional enterprise LOB application, where you may focus on one or two platforms and make that a "requirement".