The issue with the Mastery Pass is not in its value, it is the gate they put on it to earn levels. They need to let you grind it out. Most people will see there are 20 days left on the mastery pass and grab it thinking they can complete it. Only to feel really bad when they realize that no matter how much you play you cannot. The Mastery Pass should be an incentive to play, not make you feel defeated with no catch up mechanics. At minimum disclose how many levels are possible within a given week, so you know if you want to spend your money on it or not.

Ideally don't close down the Mastery Pass after the time has "expired". If you paid for it, you should be able to complete it still. Other "battle pass" systems do this. It's digital content, it only make sense at this point.