So when you add all this up and apply to all Windows PCs, it is an ongoing cost of hundreds of millions of dollars per year to the PC ecosystem, well over a billion dollars over the lifecycle of the operating system and yet by most predictions the majority of PCs will not even be capable of playing DVDs.
I believe what's really missing on Win10 is the DVD CODEC. Given a suitable CODEC, WMP may still play DVDs. VLC has all of it's CODECs built in, including one for DVDs.
For audio, MediaMonkey is an excellent player and music library organizer that does much more than WMP ever did. For an all around media player and media center, NextPVR, Kodi and MediaPortal (all freely available) are among the many options. The only caveat is that I'm not sure if they have been updated for Win10 yet.
I'll throw Foobar2000 out there for audio playback.
I use VLC for video and Foobar2000 for music. Both work great and I wouldn't use anything else. You can install to disk, or a portable device with Foobar2000. Point it to your media library (Copy files to USB first if portable.) and it will build it's own. (I like how it presents. If your media is not tagged properly, it may be a bit annoying however. Once tagged, it's wonderful!)