Well, it surely isn't a problem on the DS! Look at the top sellers on DS from Nintendo (http://vgchartz.com/worldtotals.php?name=&console=DS&publisher=245&genre=&minSales=0&results=50&sort=Total)
4 of the top 10 were never seen in previous gens. 1 is virtually a comeback from the dead (NSMB) for the 2D Mario series, and 1 is a first time on a handheld. 5 of the next 10 were never seen in previous gens.
It's a bit more of a "problem" (although I don't consider it one) on the Wii. If you exclude the Wii series, this is the case.Top 10: 3 never seen in earlier gens. Next 10: 3 never seen in earlier gens.
But it isn't like Nintendo had a 7/10 new IPs on the GC, oh no sir.
Top 10: 0
Next 10: 2
So your assumption that this was a lot better on GC isn't correct. Oh, and GBA was pretty much a remake-only machine.
Concluding:Nintendo makes more new IPs than they did last gen. Or rather, Nintendo's new IPs sell more than they did last gen (compared to the rest of the games on the machine).
(I'm aware that this is far from the best method of doing this, but at least it has some statistic substance).
Edit: Gah! My posts have been coming out like this for a fair while now... I'll fix it in a jiffy.
