The PSP Go's sales are struggling for fairly simple reasons.
You can do pretty much everything and get all the major benefits of the Go with a regular 3000 and a memory card, and most importantly, depending on where you shop, and where you are in the world, you can get the 3000 AND the memory card for a fair amount cheaper than the Go on it's own.
Then with the 3000 you can either decide to download a game from PSN or buy the UMD version based on whichever is cheapest. I have looked into it in the past and a lot of games were cheaper on UMD than they were from PSN, that may have changed now but you can guarantee that put off a hell of a lot of people at launch.
Make the console cheaper, make the downloads cheaper, and it will stand a chance. Until both happen, it's dead in the water regardless of how Sony try and spin it...
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