Among people I know, I can think of a few who rent DVDs from Redbox and watch them on their laptops (we're out in the country, so the internet isn't fast enough for streaming video). They're not technically adept enough to know that they would need something like VLC after this update.

You're correct on the latter point; the Media Center functionality (not to be confused with Media Player) was used by very few.

That said, if you have cable TV in the US, it was the best way to use your own hardware to watch cable TV.

I would care if tbe Xbox one, which will soon be on Windows 10, stopped playing DVDs. But I don't think this would be the case, there is probably a specific player for it.