Can we really blame kids for, currently, liking Angry Bird more than Mario? Mario is not, officially, on tablets and smartphones like Angry Birds. It's a consequence of being a franchise tied to it's companies hardware. Not that this is a bad thing by itself, I don't have numbers, but I think Mario is still, overall, more profitable than the Angry Bird brand, and more likely to remain consistent, since I doubt the Angry Birds brand is going to last many years.
That said, I do think the Mario brand has potential to become more know and generate more income from merchandise than currently is. They could take some pages from the book that the Pokémon Company is reading.