Terrible list OP. Those are all wonderful holidays I look forward to every year.
Groundhog Day - The day I can easily see one of Bill Murray's best films.
St. Valentines Day - A day of remembrance for an early pioneer of bringing Christianity to Europe. Also the one night your significant other is bound by law to be unable to say "Not tonight".
Presidents Day - If you think this holiday is dumb...you should be deported out of the country.
Casmir Pulaski Day - If you think this holiday is dumb...you should be deported out of the Chicagoland Area.
Earth Day - If you think this holiday is dumb...you should be deported off the planet.
Arbor Day - Trees are more important than humans. Show some respect, meat bag.
Halloween - I am appalled this made the list. Candy, horror movies and slutty costumes. Can you really name a better holiday?
April fools day - This being on the list is just probably the OP's early AFD prank.
Flag Day - See Also: Presidents Day
Columbus Day - Yeah...okay. **** Columbus.
If I had to choose, I will go with Sweetest Day. I don't need a sequel to Valentine's Day when I am busy spending money on Halloween candy and fishnet stockings.