Not really. Having heterogeneity among operating systems is better than pure homogeneity. Say, if everyone ran Linux, and some massive security flaw was discovered, we would all be screwed at the same time. However, if we ran different stuff, and some massive security hole was found for just one operating system, then only a small portion of the world is vulnerable at once. Besides, more operating systems can lead to more innovation, as long as there is good competition between them.