Fee for game: 50$
Monthly Subscription: 13$
Cost over one year: 13*12 + 50 = 206$

Average price of game: 50$
206$ is therefore equivalent to about 4 new games.

Average play time for RPG/Adventure like games = 50 hours.
4 * 50 = 200 hours.

Therefore it is reasonable to expect at least 200 hours of new/non-repetitive game play per year.

I think we are nearly at the 200 hour point, and no where near the 1 year point.

To expect more content than 4 games, for a price less than 4 games is to expect business madness. And they are not here to loose money.

COULD they deliver the equivalent of a brand new game every year: Sure
Are you willing to pay 50$/mo subscription fee to warrant that? Nope.

Ergo, the problem and compromise.