Is there a way to show all open windows in OSX 10.9+?
It's a while since I used Mavericks but on OS X 10.11.5 El Capitan in the system preferences for Mission Control there's a Hot Corners button in the bottom left corner.

Opening this I was able to assign the bottom left hot corner to 'Mission Control'. This is about as close to what I recall Expose doing as I can get.

The resulting Mission Control view makes sense to me as it shows the applications open in the desktop space and identifies the other applications occupying their own spaces.

I'm not sure I find the 'Show all Applications' option much use at all either.

Thanks for asking the question - I've gotten used to using the 3 finger 'push' to bring up Mission Control on my MacBookPro. I like the hot corner option being there.