I have the W10 Tech Preview. they don't have Media Center in there yet. Once they do, I'll (1) try it out and (2) send feedback if necesary
I've heard rumors it won't be included. There will be a separate WMC edition if it comes to Windows 10 at all.
I'm having this same issue on a Dell Inspiron 3148 laptop that I just purchased to be used as a way for me to watch TV around the house. Suffice it to say, very disappointed that Microsoft hasn't fixed this problem after so many years.
I am not feeling optimistic about the chances WMC will be in W10, I remember reading that the entire WMC development staff was disbanded a few years ago, and the only thing different in W8 compared to W7 was that they added a CC on-screen button when watching programming in WMC. I don't think Microsoft is devoting any resources to this anymore, and I can't blame them considering how the cable companies have fought tooth and nail to make it in any way easy to have TV on your computer.
However, I DO hope that Microsoft at least fixes this one problem, since it is widespread among the dedicated userbase that WMC still has. Not holding my breath though.
It's really sad that the cable companies and content providers have made it so much harder for people to record and view the content they are paying for than it is for them to just get content illegally and free.