If you don't want to pay the windows tax, don't buy the computer. They don't have any obligation to you unbundle hardware and software. Likewise, you have no obligation to buy it. It is a voluntary exchange.
Sure, don't like it don't buy it, but if there's 0% (that's zero) other option, what can you do? That's the case in practice over here in Taiwan that you have to choose between no computer, or one with Windows. That's not really a choice, is it?
Considering that in the EU Microsoft has to provide a choice of alternative browsers (the N edition of windows) I see this as more sane option that addresses the problem closer to the core and I hope that it will be required practice in the whole EU.
After all, a vendor who is confident in the value of their product has nothing to fear in the face of fair competition.
If you don't want to pay the windows tax, don't buy the computer. They don't have any obligation to you unbundle hardware and software. Likewise, you have no obligation to buy it. It is a voluntary exchange.