Thus quoth RIM.
Sony's problem has been and always will be implementation. They just don't know how to streamline the functionality and delivery a high-value product. They try way too hard to be all things to all people rather than sticking to a single design motif.
I agree with everything you say, except this para. I'm not sure it's far to say that lack of focus has always been Sony's problem. The Walkman was a damn near perfect design. It did everything it needed to, and nothing it didn't. Accordingly it defined the market (though one could argue that the rot set in with the Megabass control).
I'm also leery of favouring Sony with the "all things to all people" label. There are plenty of CE companies for whom that is a suitable epithet. Sony started to get into trouble when they tried to limit stuff. Proprietary formats and lock-in killed Sony. Apple are guilty of the same of course, but Apple bring value. You accept the lock-in and lack of broader compatibility because life is pretty decent in the world of integrated Apple devices. Sony has long been at war with itself, so the lock-in didn't even help people who stuck with Sony products.
Unless a closed/proprietary system brings a lot of value add, being open in always better. Sony still haven't internalized that message.
Apple have, but the lesson they've drawn is "get it right".