It's HTML and CSS holding 'web apps' back. It's like we're all trying to sharpen our pencils with spoons.
I think the future of remote web-like apps lies in something like QML[0]. A completely native UI with full access to the desktop widget suite can be downloaded in QML in a few kilobytes. Stick a browser like loader on the front of it, and provide a decent (seamless) asynchronous RPC, and you've got yourself a replacement.
Spawn off a rdesktop or VNC session back to a cloud based server. Skip all the intermediate interference that just slows down and complicates things, and turn the web into a dumb graphics terminal. You can either intentionally use the correct tool for the job, or painfully slowly buggily reinvent it if NIH is a requirement.
I think the future of remote web-like apps lies in something like QML[0]. A completely native UI with full access to the desktop widget suite can be downloaded in QML in a few kilobytes. Stick a browser like loader on the front of it, and provide a decent (seamless) asynchronous RPC, and you've got yourself a replacement.
[0] http://doc.qt.io/qt-5/qmlapplications.html