I agree with Peachie in that ouija being nothing more than cardboard.... items such as those only have as much power as the intent to have the item. A napkin or sheet of paper and a pen can have the same purpose as an ouija, it doesn't make a piece of paper and pen evil.
That said, I also wouldn't want one in my house, not because of "its evil" I just have no need for one and any "event" or joke at work that needed one crosses the line of "intent" to "jokingly contact the dead" or even serious intent to do so.
Im sure that all "fun" could be had and nothing bad come of it. However, IF we believe in spirits, if we believe that demons and devils exist.... why even give those spirits a foot in the door.... no matter how slim the chance anything might come of it. Why chance it even if its only a .0000000000000001% chance? Sure the numbers may be in your favor.... but even if its 1 in a billion chance....... what if you were that 1... was it worth it?
Same reason I never swim in Galveston beach..... sure, the odds of a shark are so very slim... but given the look of the beach, the tiny waves and the disgusting look of the water..... even the slim chance isn't worth it for the 2 seconds of fun I MIGHT have in the water.