Do small tiles in WP8 not animate?

This has been bugging me for a while and I was wondering if it was actually documented, expected behavior. I noticed that:

1. Large tiles and medium tiles animate and are updated live
2. Small tiles sometimes update the front of the tile and sometimes just show an icon
3. Small tiles are never animated to flip from front/back

Is this designed behavior? It seems 2 and 3 may be related wherein the front tile of a live tile is the icon, which is why it ends up getting shown the whole time.

And if this is the designed behavior, what are people's thoughts on this? My initial guess is that MS expected people to pin a LOT of small tiles on the screen and that animating all of them could cause battery issues. Or maybe a jarring experience because everything on the screen would be flipping.

Personally, I think tile flipping should be agnostic of the OS. Meaning that if I wanted the small tile to flip, I should be able to set that. Similarly, if I do not want a medium/large tile to flip, I should be able to set that, too.