Rather than blame the moderators, how about blaming the people who caused the thread to be locked? If you criticised them when they did it, and told them that they were spoiling the discussion by saying things that will get the thread locked, perhaps this would approach a level of 'user moderation'.
Now my question for the moderators is this - Can a reason please be given at the end of a thread when it is locked? Or is this not done so people don't have a go at the moderator who locked it?
Cheers