Sean:
At one time, Crystal Downs was all gang-mowed at the same height -- probably 3/4 inch fair/rough. I doubt that was really the original intent, just a practical solution to Depression finances.
The trees both left and right were there when the course was built -- they were (along with the tree in the corner of the dogleg on
"street trees" planted along the old road that went through the property, which was moved around to the east when the course was expanded from 9 holes to 18. They were reasonably big trees in 1933 -- twenty feet tall at least -- so it's not like Maxwell or MacKenzie just missed seeing them.
The bunkers to the right of #6 are really just eye candy, with the tree there ... you have to either play around the tree, or hit over it, as I've seen a couple of people (including Ben Crenshaw) do over the years. The trees on the left do occasionally come into play for me when I yank a tee shot to the left, but there's 35 yards of fairway and several yards of semi-rough on either side before you get to the nasty stuff.