Iwata recently commented on their shift away from purchasing studios due to talent leakage. After they bought Retro, for example, a lot of talented staff ditched the studio. He said they've now moved toward partnerships with proven studios instead of buyouts, which seems to offer better results.
edit: Dang it, EatChildren!!
Still, Retro today is still quite talented.
I do agree that Nintendo should get an additional "western" developer or two.
This strategy alone has paid Sony dividends and may be one of the main reasons Sony had great software for the PS3 - because those western studios they bought during the PS1 and PS2 days gave games that catered to tastes.
Can anyone imagine where Sony would be today, after the PS2, without the Uncharted inFAMOUS Killzone games etc...exclusive for the PS3? I can imagine more than a few gamers would have opted not to purchase a PS3.
This day and age where third party exclusives are not abundant as they were in the PS2 era, first party exclusives are more important.
That said, from a business POV, I do agree with Iwata as well. Talent does leave any acquisition because there's always someone who doesn't agree with the new direction of the company especially the creative ones, don't like working "under" someone else's fixed design. They tend to leave to be "free".
I still feel he is only building these strong foundations only to eventually acquire the right company when it comes along -- he is certainly not against it as under him Monolith Soft was acquired by NIntendo.