For Apple to commit to anything in advance, let alone Windows support for a brand-new peripheral, would be evidence of takeover by pod people, and thus not nice at all.
Windows support for the original iPod arrived two years later.
Again, they were testing the market with the true believers. The music industry viewed the 2-3 million mac users back then as a nice microcosm they could experiment on. If it failed, it wouldn't get much press because back then nobody used macs.
I can't imagine this would affect actual sales though, just another of example of when Apple's secrecy can be irritating for some of us.