What qualifies as an "embedded system" to me? Basically, a system where you have little to no control over the software.
Let's take a PC. I build my own, put my own software on it, do as I like. THIS IS THE RASPBERRY PI! It comes with a slot for an SD card or whatever, which you use as your hard disk, and you have FULL CONTROL over it. What goes on the raspberry pi's "hard drive" is fully under the owner's control.
Then you get locked systems. My wife's just acquired a Google Nexus 7. I'm not going to bother rooting it, but the point is that it is not easy to access its "hard drive" and change the OS or stuff like that. Would you call a Nexus 7 embedded? To my mind it's far closer to embedded than the Pi!
Then there's what most people consider embedded systems. That come, for all intents and purposes, with the software hard-coded in ROM.
By my definitions, an embedded system is perfectly okay with the GPL - no-one can update the software, so there's no problem.
Equally, an open system is perfectly okay. Whether it's a PC or a Raspberry Pi, the user has FULL ACCESS to the hard drive or equivalent, so can update things as they please.
It's the things in the middle, like the Nexus 7, that are the problem. If I can download apps, and get access to the source, then that's fine with GPL2. If I can cross-compile the source and replace the original version of the app with my version that's okay with GPL3 too. That's probably possible with the Nexus. It's probably NOT possible with the iPad.
And that is the crux of the problem with these locked systems. The LGPL requires that you have the ability to modify PART of the app. So if you can't replace the LGPL library (like you probably can't on an iPad), then the LGPL is useless for iPad apps.
I think the trouble with your view is that your definition of "embedded" is very different from most. To me, the Pi is very much an open system - I have full access to the hard disk. Its small size makes it very easy to embed it in a box and make physical access difficult, to the extent that it would be reasonable to call it an embedded system WHEN PART OF SOMETHING ELSE, but the Pi on its own is, imho, absolutely NOT an embedded system - as I say, it's an OPEN system.