It was a quick throw-together title to have out at launch like Steel Diver (DS demo turned into a game) and Pilot Wings (Wii Sports Resort-mini). When was the last time Nintendo had a well-prepared launch lineup? SNES/SFC?
Wasn't the SFC launch *just* SMW and F-Zero? Admittedly, two great games, but still...
I recall there were explicitly six titles for the European launch, although I forget exactly what they were. I think Super R-Type was one.
N64 was similar, wasn't it? I recall Mario 64 and Pilotwings 64, but I don't think anything else was at launch.
I do wonder if actually that's one of Nintendo's issues - pushing so hard to get games out at launch when perhaps a smaller focussed set of launch titles might be smarter, allowing a month or so extra for polish on the rest of the range to keep interest up.