maybe
nintendo
has
a plan.
and, you know, it's not as if those games appeal to entirely the same group of people. take me and my friends, for example. we loved us some mario kart 64. didn't really care for mario anything else. i'm sure ssb and smg are sort of the same way. and, if my recollection is correct, according to npd, ssbm sold something like 13 trillion copies or some such number, and sunshine only pulled two or three dozen. whatever the actual numbers, ssbm was considerably higher, so it certainly sold to different people.
i think this release schedule is fine.