I can't think of any good reason for them to be there . . .
I"ve only played the course once, but my gut says the fewer trees the better, especially at a course like Shinnecock. But please leave the tree behind the 7th green, it is just so cool looking!!! A cool looking single tree is a lot easier for me to like than a big grouping of very pedestrian looking trees . . .
Tom, my response must have come just as you were revising your initial post . . . I really do love those "lone" trees
-Ted