... Just not a *huge* demand. Most general "computer users" don't give a flip about their keyboard, and would rather get a freebie from Dell [1] when they get a new PC or a $10 Walmart cheapie than pay the $80-$120 for a new keyboard that doesn't suck.
[1] and Dell isn't going to bundle a freebie $80 keyboard...
http://www.clickykeyboards.com/ (For refurb/NOS keyboards)
http://www.pckeyboard.com/ (For newly made keyboards)
I bought several for $5 each @ the local university 'garage sale' almost 15 years ago; I have yet to have one fail.