Well most of the list is made up of permabanned spambots/obvious trolls and the like, from what i've read. I wouldn't say much "trigger happy" banning happens at all.
Although i do support the idea in the OP of ban reasons being more informative sometimes - i've seen a few bans on the list with the reason "fail". I think it's fair to say that every ban should be justified with a published reason, however obviously bannable the offender was.