It does actually make sense.
You can argue that "Pro" users might not necessarily need all the media things, so MS does not have to pay licenses for things the users wouldn't use either way.
Pro is also what MS hopes companys will use, which (if adopted) is quite a lot of licenses.
Licenses are usually paid per shipped copy, not as a big one-time deal. So by not including it in every copy of Pro, MS saves money. And if people then buy the add-on, MS makes money. Win-Win for them.