IS HALLOWEEN A HOLIDAY?

A couple of communities in this area have chosen to designate tonight (Saturday) as the night for trick or treating rather than tomorrow which is actually Halloween night. Today's newspaper published letters from some angry townsfolk who are appalled that anyone would have the nerve to tamper with a "holiday."
This brings to mind a couple of questions. One being: Why would anyone get so upset as to write a letter to the editor over such a minor 'issue'? Another: Is Halloween really a 'holiday' or is it just a day we designate to dress in costume, troll for candy and drink a lot? (People who need an excuse to drink a lot are weak. Strong-willed people like me need no excuse.)