There are folk that are upset about that. I get my VLC Player from ninite.com.
Here's why -> http://www.howtogeek.com/201354/ninite-is-the-only-safe-place-to-get-windows-freeware/
Now as to why. I can't guess what DVD decoder you had before. But many need to be updated or reinstalled on Windows OS changes. That is, I saw this from XP to 7, 7 to 8, and 7 or 8 to 10.
Following Windows 10 upgrade, copy protected DVDs will not play (I receive a "DVD: copy-protected failed" message). The DVDs that are not copy-protected play and both types of DVDs played before the Windows 10 install. Any solutions??