I think people are attributing the low sales of Excitebots to the wrong thing. You don't have to announce and hype a product for months to generate sales. It is entirely possible to announce and release something, blitz the public with marketing and sell millions on the first day. It happens with other products, and it can be done with games, too, if someone's actually willing to put the marketing muscle behind it.
It wasn't the short period between announcement and launch that hurt Excitebots, it was the extremely anemic marketing. A few screenshots and videos, cover of Nintendo Power, and that was pretty much it. No frontpage news on any gaming sites, no online ads, no tv ads, no radio ads, no retailer promos or deals, no sales circular announcements, nothing. Let's face it, Excitebots had shitty marketing. It could have been announced 2 years ago, and it still would have sold just as bad.