Of course Linux would never have a full native Windows API, just as Mac OS would never have a full native windows API, as the Windows API is part od Windows, a Microsoft product, and Microsoft will keep it to themselves to maximise the financial gain of having developed said API.
As for Linux, it's great, but with the much larger number of programs written for Windows (especially games), Linux has a uphill struggle to be adopted by the average user. Add to that the suprisingly large number of open-source projects that have no Linux installer and expect Linux users to do their own compiling, and you soon have a situation where most people are put off it. As for the other altenatives, most of them are unheard-of outside specialist circles, and the one the is, Mac OS, is locked into Apple hardware. (remember, as well as trying to get computers with Linux, Dell also tried to get them with Mac OS, but Apple told them to get lost).