That's probably something that the PC clone vendors of the early Windows era (1990-95) would have loved to do, but they just didn't have the software competence.
Developing a new shell for Windows was technically possible, but must have seemed like an outlandish prospect to companies like Compaq or Dell. ("Where are we going to hire a bunch of C developers who know GUIs and can do a better job at this than Microsoft? Forget about it.")
Some companies did go there -- for instance, HP had an advanced Windows shell called NewWave [0], but I don't think they ever built PCs specifically for it.
Today, the situation is very different. The executives at any old phone maker will look at Android and say: "That's just Java, isn't it? We have plenty of people who know Java. Hell, there's a school down the road where they train 100 Java developers every year. Let's do it! We can be a software company too, just like Apple!"
And of course we know how that turns out. But it will take a long time until the executives at all those LGs and HTCs will recognize that their organization sucks at software, because it's not a software organization at its core. (Nokia spent tens of billions of dollars on Symbian and MeeGo until they finally got this lesson, and they ended up selling the phones to a software company.)
[0] http://en.wikipedia.org/wiki/HP_NewWave