Like Seto said, we wouldn't allow topic deletion because it has been abused in the past (that is the reason why we disallowed it on Excoboard). Locking would be for about the same reason; people disliking comments that aren't necessarily against the rules lock their topic for childish reasons. These tools are in the Moderator CP for a reason, and the Mods are just fine with doing what they do. Its their job.
Also if need be, there is always a place that we can send topics to for staff discussion before putting it back into circulation.