The question is, why do software houses and retailers suddenly feel the need to turn into device vendors, taking on the very different economics of that business, and making themselves reliant on a mobile manufacturing partner while alienating other platforms for their services?
Google, Facebook and Amazon all have the reach to make their offerings ubiquitous on every mobile device around, without having to own the hardware itself. And they might have learned some lessons from Google's Nexus experience. If they try to be too disruptive, bypassing traditional channels or angering other mobile partners, they can actually reduce the reach of their key services. Yet if they do not do something radically different, there is no point having their own phones at all.
There is an element of Apple envy, but none of these web firms can emulate the integrated hardware/software experience of iOS because they are working with open source platforms and web services, not a closed environment. Their huge reach and influence depends on that, yet they hanker for at least a little of the iPhone maker's control.
So Amazon and, reportedly, Facebook will use their own tweaks of Android, creating their own user interfaces and developer platforms. The plus side – a user experience optimized for their particular offerings; the downside – fragmentation of Android.
So, we may argue that these companies are excellent at delivering services across multiple platforms, with a strong and consistent user interface – and moving into hardware will only compromise those strengths. The proof seems to lie in Nexus, now largely a showcase developer product rather than a mass consumer device; and even more in the conflicts, internally and within the Android community, which Google will face once it completes the takeover of Motorola Mobility.