IMHO, Japanese post-war consumer electronics bloom is simply a matter of being at the right place, at the right time, with the right resources, and leaders with the vision. However, the time has passed, and the manufacturing advantage had been lost. And the market has gotten more sophisticated.
Japanese electronics cannot be compared with Japanese auto as they started quite differently. Japanese electronics are overengineered compared to almost anything else contemporary... back then. They are almost like the old MBenz... engineered to last 20-30 years. And they use that engineering to pack in even more features. The smallest Walkman, I remember, was barely larger than the cassette tape itself. And use a SINGLE AA battery!
Japanese auto on the other hand, started as econoboxes (for local market) exported to fit the post-oil embargo fuel economy market. In a certain way, they are polar opposites. The electronics started high and tried to work their way down, while the autos started low and tried to work their way up (Toyota, Nissan, and Honda spawned Lexus, Infiniti, and Acura...)
But Japanese electronics suffered from its consumer-orientedness... and its perceived premium status. When Korean and Chinese cloners got enough prowess to infiltrate the low-end and work their way up (exactly the opposite of Japanese electronics) Japanese electronics makers can't really compete except outsourcing their manufacturing when they can. So there goes the low-end. On the other hand, they don't have a lock on the extreme high-end either.
Speaking of Sony, one could say it haven't made a right bet in decades, one mis-cue after another. BetaMax and MiniDisc are probably the best remembered examples. Any one remember the Palm PDAs they made? The Sony CLIE series? Died on the vine. MemoryStick? Nobody uses it except on the consoles. ATRAC music compression? Nobody remembered it (everybody knows MP3). They even joined Android game late.
Arguably, the ONLY major success Sony had in recent years is the Playstation series. And even that was marred by the "Playstation Phone" (Android phone with Playstation style control pad, but requires its own game library)
This may be something to do with the Japanese psyche. I remember a while back I read Nintendo's design process. They have three teams, sort of competing and sort of alternating with different projects. And that somehow brought us Virtual Boy... a true disaster of a console that's neither handheld nor full console, neither fish nor fowl. Marketing overpromised and engineering underdelivered. I think they are assuming that the consumers will adopt whatever they put out, almost like fashion/ couture or car models , and they are "surprised" when the consumers didn't follow.
And it seems Sony was doing the same thing, and same with all the other makers. They are engineering stuff WITHOUT regard of consumer needs. This may work when consumers are fairly unsophisticated, but it's a "self-liquidating" market. Soon consumers will demand more.
Now that the technical / engineering prowess of Korea (and China) have caught up (at least somewhat), Sony can't really compete on the low-end, and is barely holding its own on the high-end, if at all.
I used to have a VAIO laptop. It was great... Until the DVD drive failed. It has features that I never used... such as the i.Link (i.e. Firewire) port. Or an actual 56K landline modem... and so on. Or custom launcher button I can designate to launch a particular program on demand (never used that either). It is as if they are engineering features just for the heck of it.
And that's the lessons they need to learn... quickly.