The #1 priority should be to keep the harmony of SN, on SN.

If you try to make it (more) competitive by introducing a leader board and strictly reward people based on their placement on said leaderboard, then it could lead to said harmony going under in the long run, as competition can attract some very unwanted types of behaviour.

The daily rewards were a nice personal type of reward, as in:

"you did well that day by providing value, in one way or another, to other users of SN, and therefore you're rewarded extra. Keep it up."

I can't quite put my finger on why I dislike MSM now, but I'd gladly take the former system above it, for I feel that it'd serve SN as a platform, as well as it's users, better in the long run.