Honestly WMP is a bare minimum DVD playback experience, and most people don't even know it is bare minimum experience as they don't even know how to watch DVD using WMP. WMC may be ok, but, we really need to consolidate the experience to Metro to reduce customer confusion. That and tablet, netbook, and ultrabook have no cd rom. And all notebook and DVD Rom retails comes with their own DVD player anyway. While I do miss it, but, I don't think it is that important to bring it back, not with current lackluster experience.
BTW, this app, TKS Media-Player, seems to support DVD playback for free. For now, just get those if you managed to buy a DVD player without software.