Whilst I follow your logic, can you point me to an Android phone (one single make/model) that currently achieves sales in excess of 18-19% of the total market, rather than the numerous makes/models that have jumped on the Android bandwagon and are scrapping around for the minimul market penetration that their brand and model can achieve.
Looking at the profits that the companies that the "managers/service designers" work for, I'd say that they have got their strategy spot on, and I can't see that changing anytime soon....