THIS! It's the ecosystem. Niche phone OS is not going to dominate the market until they have a competing app store that as good as Android's or iOS's. People

THIS! It's the ecosystem. Niche phone OS is not going to dominate the market until they have a competing app store that as good as Android's or iOS's. People uses Adobe will forever bounded by whatever OS Adobe truly supports. People uses MS Office will forever bounded by whatever OS MS Office truly supports. Nobody really cares about UI. Everybody hates new UI. Once you are settled in the local comfort zone of the app that you use the most, nothing else would replace it unless that app goes out of support.