The points have decreased because we've fixed the code for the "Discussion Starter" achievement set. It is now indeed working as intended, so a lot of people that have had the achievement lost it.
As for "You made all this possible" achievement set, I don't understand the problem. Are you missing something here?
The points alloted per achievement are calculated based on the number of users that have them. More users have a specific achievement, less points it awards. This is recalculated after each achievement update.