Golden-i is a full PC, runs MicrosoftOS. offers unique Hands-Free user interface: advanced speech recognition in 26 languages with 6 axis gesture recognition.
As developers placed the first generation of their apps (and data) on Windows, and as the amount of MicrosoftOS based data grew, so did the value of the Windows ecosystem and of each successive generation of apps.
The reason, at least in part, that there was so much written for MicrosoftOS was that it was such a popular OS. And as other OSes become more popular then I would expect to see attention being paid to writing malware for them.