The reasons why would be that it is always peaceful, many cemetery's are quite beautiful and you may get a great property for less than if it were in a different location.
The reason not to is that it could narrow the buyers you would attract as many find it disturbing to be reminded of those that have passed. Whenever you purchase a property that is "out of the norm" it will narrow the buying public, however, there is always a buyer for every property. So when it is time to sell, take into consideration that it may take extra time and marketing.
Are you looking to purchase near a cemetery?