It would be nice if the maps could still be kept in order of the week they were discussed, and still be able to most posts on them.
That isn't as simple as it seems.
It would be possible to keep the current MOTW on top by making the current MOTW a sticky or an announcement. (no change to phpBB necessary). But it would imply that when a new MOTW is started, the previous one would have to be edited to remove the sticky (or announce).
Keeping the the MOTW in the order of topic start-time is a more of a hassle and needs and extra sort order (and I can't remember offhand whether the variable topic start-time is available by default in the calling php). All in all it's not a difficult modification but I doubt it's worth the effort (with every update it would have to be checked).