Well, I thought that it was common knowledge that Amazon spreads access widely. AFAIK it's also available on iOS and of course e-ink readers. That platform indirection is a strong reason why I would make an Amazon purchase instead of Play. Similarly, lack of device access for Play (Roku, TiVo) is another reason I prefer to purchase video content on Amazon (I've been purchasing subscriptions for series that are automatically delivered to my TiVo in lieu of cable subscription for a few years now). Not to mention that Play's handling of music does byzantine obtuse things on my phone whereas Amazon MP3 is quite sensible in its directory and file naming. Amazon just feels more open and accessible. Not to repeat the biggie--responsive customer support.
And do you realize that you can't download kindle books on to them unless you already own a kindle device. That app was only designed for portability of your existing library. Amazon in no way give up their biggest advantage over android devices.
That's not true. I don't own a kindle device yet I have books I purchased on the Kindle store (when Amazon had a sale in the past) appear in the Kindle app on my Nexus7.
Maybe it's just that the app does not allow purchasing (never looked)?
How do you manage to get the books the at the kindle sale price when you don't own a kindle? Strange, when I got my Nexus 7, I did give the kindle app a try but it wouldn't let me purchase any books unless I paid the hardcover price. I have amazon prime, but without owning a kindle device, these ebook sales are meaningless to me.
The app allows purchasing. If it didn't, that wouldn't benefit Amazon (see: iOS).