I think it is pretty simple: they want money. If they make compelling content I have no problem with it. I personally am of the open source persuasion, but some people just don't understand yet that money comes from more people hearing/seeing your work.
Is there ads on the paid content do you know?
1. something that is contemplated, devised, or planned; plan; scheme.
2. a large or major undertaking, especially one involving considerable money, personnel, and equipment.
3. a specific task of investigation, especially in scholarship.
4. to propose, contemplate, or plan.
5. to throw, cast, or impel forward or onward.
6. to set forth or calculate (some future thing).
7. to extend or protrude beyond something else.
8. to use one's voice forcefully enough to be heard at a distance, as in a theater.
9. to produce a clear impression of one's thoughts, personality, role, etc.