only if money is the end goal
As a retail or manufacturing shop, money would be my end goal so retail market share figures have some basis. It's all just units to be shipped in return for profit (the real company product).
From a user perspective, how much money a product made for it's parent company doesn't provide any valid quality or functionality metrics. osX tends towards a better user experience but it's retail market share is smaller than Windows. The percentage indicates popularity only; no relation to product quality or functionality.
I always giggle a little when someone's entire claim boils down to "but my choice is more popular so it must be better". "The market" is a terrible indication unless, and only when, debating retail business metrics unrelated to the end user beyond them being the source to harvest little green pieces of paper from.
