it may have started when they made cheaper versions of previous stuff before a new release. (PS1 slim, PS2 slim, PS3 slim) that were inferior quality and was some sneaky way to get us to upgrade when a new item was released. it seems they 'slimmify' their last item (DVD, Blu Ray, PlayStation) before they release an upgrade, likely a year or so before. they think that if the item breaks the user is going to buy the new replacement. but after three PS3s did the Yellow Light of Death failure, at a cost of $249 per unit, I decided to stick with Xbox. I still like Sony's consumer items, such as clock radios, stereos and such, at least they seem well made enough. but they hardly have any products unique to their line. they got Blu Ray, which won over HD-DVD (unlike their previous attempt with Betamax vs. VHS in the 80s) but that's pretty much it. everything else is common everyday stuff (TVs, game consoles, stereos) and nothing inherently unique like the Walkman or Discman were in their day. my first CD player was a Sony Discman.
ever notice the prices of Sony products is getting lower? they no longer have the preference of the higher end part of the consumer market the way Bose still does today.
then you got the problem with trying to support too many products at a time. the PlayStation Vita for example. it's sadly going the way the Nokia N-Gage did in the early 2000s, with a great launch but no support later on, and it still has very few games available. Sony is trying to single-handedly support the PlayStation 3, Vita, and now they are focusing on the PlayStation 4 so much they can't keep up. it's also a problem that caused Sega to get out of consoles. Sega had great consoles, the Saturn and Dreamcast, but failed to follow through in the end, much like Sony is going with the Vita.