While this doesn't affect the experience on stock Google devices, phones such as the Nexus line represent a crushingly small share of the market, so it doesn't matter.
In addition, I don't understand the pivot towards elevation. The industry has been moving towards flat design. I like flat. It's simple. Less design is often better than more deisgn.
The new Gmail design is a great example of this. The current design is simple. Information is there as soon as you open the application. The new design has increased usage of whitespace and a larger action bar, not to mention that intrusive icon in the bottom right.
There hasn't been a single thing about this year's I/O that has impressed me, or pleased me for that matter. Disappointed that Google continues to pump out new features instead of perfecting the ones they already have.
The way I currently see it, you have Apple putting out less features with incredible levels of polish, or Google throwing features at the wall until something sticks and then only enhancing it a little (i.e. Hangouts).