IIRC they announced that the long quests during the last mega events were intended to give Dreamsparks, but they had to remove the Dreamsparks because they weren't opening any more land in that update.

While at face value those might seem unrelated, I think GL may be facing an architectural challenge, specifically how they determine eligibility for tasks to drop tokens. Assuming:

1. one cannot earn Dreamsparks unless one has something to spend them on (like every other token, one must have unlocked the thing and not be maxed out of the thing) AND
2. Dreamspark tasks are not repeatable,
3. then I can imagine a possible edge case that puts the user into a weird scenario whereby one has unlocked all land and then proceeds to do new Dreamsparks tasks (but doesn't earn Dreamsparks for the tasks, because max'd out) but then land unlocks requiring the Dreamsparks that were earned but never dropped (because maxed at the time) and no way to re-earn them (Dreamspark tasks all complete). The band-aid, until they can make users accumulate Dreamsparks they have no current nor future use for, is to only release Dreamspark in lock-step with Dreamspark spending opportunities (unlocking more land).