Android itself isn't a bad decission for embedded devices with a touchscreen and Sony did a good job with their T devices. What is bad are Google Play services, vendor spy/bloatware and having a bunch of apps running in them. Sony killed all these problems shipping a "closed" version of android 2.2.
Another nasty choice that some vendors do nowadays is choosing a platform with deficient power management (rockchip), a platform with known issues handling cpu freq (allwinner) or a platform without sources at all (mediatek). Sony used freescale like Kindle, Kobos, Cervantes, Tolinos.
The java vm used in android has nothing to do with the standalone Oracle/Sun machine. It just happen that both are compatible with bytecode for java7. The old one was
Dalvik and the new one is ART.
The sad thing is that most e-ink devices with android are promoted as "Android with Play Store" and use that as an excuse to ship bad reader software.