Well, you did say an Amatuer designed the course....
It looks like the Ravine behind the green caused him some troubles in the routing and my guess is that he left the tree to try to add something to what he felt was a weak hole. Is it an Oak? The vase-like shape and the thick, white streak down the trunk makes one think it could be an American Elm. Both can live well past 100 yrs and this tree has undoubtly reached it's mature size.
Features on a course should have some reason for being. It is up to the golfer to ascertain what that reason is. In this case there exists 2 Features However, given the horizontal nature of the green, it is redundant with the frontal bunker as both require a high arcing shot. I would imagine that most players know about how FAR their clubs go but not how high or where the apex is.
Being in the camp that only one option is actually no option, I would vote this to be a poor design. As Mr McBride states, it's too hard for slow clubhead speed to generate enough height to clear it and there is no ability to go under or around. Plus, one on the tee is indeed sheltered from wind but, given the height of the tree, a ball hit over it will encounter wind that is all but impossible for the player to gauge.
I also disagree that it would be a boring hole without the tree. Just leave the bunker and eliminate the artifical mounds behind the green to highlight "death beyond" and it would be an equally psychologically demanding hole. Being a public course, a shelf bunker or grass ledge depression could be cut into the slope behind the green as a Saver.