Material animations are not (entirely) pointless, they are designed to improve user's awareness of UI's behaviors - primarily by making transitions between related screens less "beam-me up, Scotty" Teleport-like.

Sure, it may be prone to abuse, but the base theory is sound. By tapping into the perceptual abilities of movement and shadows, some parts of the inner structure and layout of the interface (which are usually only known to the dialog's developer) are exposed to the user in an intuitive way.

What's some of the best UX design you've done? Can you tell me about affordances, and why the Materials design falls short on them? On desktop? On touch devices?

For us developers, a command line and vim (or emacs, not trying to start a war) can be the epitome of UX -- once we learn all those shortcuts.

But for users, there's a lot more that comes into play. Indicating to a user when something can be interacted with and - more importantly, many times - how it can be interacted with is very important. Usually such indications will also inform about what kind of result will happen from the interaction: will the form submit, will the page reload, will I see a list of additional options?

Just as important is indicating to the user that yes - you just interacted with something that can be interacted with. Depending on the action, this can be something as subtle as an underline - or as obvious as showing a loading indicator.

The Material animations aren't just eyecandy for the sake of eyecandy. While touch screens are getting better, there are still situations where a touch doesn't necessarily register as a touch. It's super important to indicate to the user that a touch has been registered. It's just as important that this happens immediately, instead of after - say - a round-trip request to a server somewhere.

If you've built and designed a user interface that has amazing affordances, a general perception of 'speediness' even if the server is being slow, and treats touch users as a first-class citizen ... I'd really like to see your work!

We do need to let users know a touch has been registered. In some cases all you need is a color change. Other time, a slight fade in or small animation. But having content areas fly in for almost a whole second is overkill. That's why this site is a poor example of the technique.

  having content areas fly in for almost a whole second is overkill

...except for those cases when it's not. Major context changes such as switching applications benefit from more explicit animations, that physically convey where everything goes or comes from; those can run from less than half a second to about two seconds for more showy "Welcome to product X" screens. If the old interface simply disappears, the user has no clue on how to restore it. That's why you get nifty "minimize" animations in all modern desktop environments that care about more than processor cycles.

In the Material design, animations are also intended to increase affordance by showing what areas are interactive, without requiring the extra chrome of everything having 3D borders.

I think you misunderstand. I'm not against animations. The minimize animation in today's operating system is a perfect example of how animation can simplify the user experience (although I do think the OSX shrinking animation is a tad dramatic). But keep in mind, those animations are still short compared to the examples here. Whats more, the linked example uses the fly in animations for interactions without major context changes. Switching from pages in a document is hardly the same as switching applications.

I think that a compromise can be found, just check out Lollipop to see a successful example.

There are some glitches when animating layouts. The "primary action button" (is that what the floating circle was called?) sometimes covers the scrollbar after resizing the window, and jumps around on mouse-over; and when the browser window is not maximized, after selecting an option in the left vertical menu, the floating panels jump around a lot vertically before stopping. I'm using latest Chrome on Windows 7.

That's up for debate. I have disabled the animation in L as they were too distracting.. Although I like Material Design overall.