I generally agree with you, Chris, but the Japanese maple trees that are old, well maintained/trimmed, have a good background, etc. are not necessarily easy to find other than at Japanese gardens. I agree that the one in Portland is way overhyped and overshot, but we have to admit, it has a nearly ideal shape, background, and position in relation to ambient light. It all greatly matters with these trees.
What I really have a problem with related to the Portland Japanese garden is that they charge a lot ($16 general admission) to get in, and on top of that, they charge $5 for tripods. To me, along with crazy amount of photographers shooting that one tree, is a huge turn off for that place. Kubota garden (where I shot the tree above), contrary, doesn't have any entrance fees, tripods are allowed and no extra charge, and when I was shooting this tree, there were only two other photographers there.