You seemed to have somewhat missed what I wrote.
The overarching aim doesn't appear to be to bring in audiences that aren't being attended to by third parties. It's to ensure there is an audience, and strengthen that audience, for third parties.
It's about positioning and branding the platform as a home to a diverse array of core games targeted at males, aged 15-35.
It's the same approach Microsoft have adopted from them. Halo complements other first-person shooters on the XBOX platform as much as it competes with them.
It's the approach that Nintendo have seemed reluctant to do; although with publishing Bayonetta and funding more titles like X, perhaps they're finally doing so.
Why would third parties turn up? Well, they have for three generations of home console. And there's relative certainty they'll be on the PS4 and XBOX3; while a cloud hangs over the Wii U.
Why has such an approach failed on handhelds? I would say it's because, fundamentally, Western third parties aren't interested in handhelds; and similarly, SCEWWS does not focus on handhelds.