REASON #1: Weekend Halloweens are ideal for everyone, especially families.
REASON #2: A Halloween weekend is good for local business. With time and proper marketing, a Halloween/Fall Festival weekend of sales would decrease the frenzied pressure that has gone into November's Black Friday, and allow employees and shoppers a more relaxed holiday shopping experience.
REASON #3: A separation from the Christian holiday All Hallows' Eve. Having Halloween exist separately might appease more conservative Christian Americans, in addition to appealing to those Americans who would rather not have religious overtones associated with Halloween.
REASON #4: There's a precedent for changing holidays if a compelling reason exists, in the form of the Uniform Monday Act of 1968.