The free rolls are a monthly thing if I understand correctly, so each month we will have 6 days of FM rolls and 6 days of knight rolls. As for why, they are likely getting ready to implement some new monetization strategy. Since last time it backfired hilariously, my guess is that they're giving it to us in stages rather than all at once, starting with the generous player-friendly features. Alternative theory is that they're seeing metrics that indicate that a lot of players aren't logging in daily and that player's who log in daily are more likely to whale, so they are implementing features that strongly encourage daily login.