I love Morris dancing and I would like to bet that it's actually been around for longer than just the fifteenth century.... the dances are to do with crop fertility and animal husbandry and different dances are tied very closely to different parts of the country. I danced with a Morris side some years ago but it is extremely energetic and terribly suited to the female frame and I got shin splints as a result. There is a lot of leaping around and stamping involved :)
I think old traditions like this are very important and should be as well preserved as possible. We are losing so much of our heritage, particularly those forms connected with the countryside, and that saddens me enormously.