I have a million reasons. It's a day out of the year to show your imagination off. And to be someone else for a day. If you wear a costume to work, it not only gives people that see you day-after-day something new to see you as, but after its all over and the next year rolls around, people can say they remember the previous year when all the madness happened.
Also, it's fun to get all the candy. And it's interesting to learn a little about different things. Because costumes and the crazyness always lead to conversation.
I also like it, because the day after is my birthday so people never forget my birthday. And if they do, I don't mind so much because I have a lot of candy surrounding me that I can scarf down for "comfort food".
And let's not forget all the awesome scary movies that come out in the theatres or the endless hours of movie marathons on tv. And the ghost stories that kids sit around camp fires telling to get a good scare. Also, in the adult world, Halloween is also awesome because there are parties every where. You can show up sexy, funny, weird or scary. People love to compete and have fun exploring all the excitement.
Seriously, I don't understand people that DON'T like Halloween.
I could go on all day with this.