The mistake Microsoft made was to stubbornly tie user interface convergence to their platform convergence effort. Everything had to be Windows so everything got

The mistake Microsoft made was to stubbornly tie user interface convergence to their platform convergence effort. Everything had to be Windows so everything got start buttons and all kinds of cruft that wasn't needed and lead to bad experience. Making platforms more similar so it easier to target that platform is very nice for developers. If you can do it without losing what makes users want the different devices then there's no downside.