Conceptually I have never minded trees encroaching out on the fairway a bit. You can still advance towards the green IF you can hit the requisite fade or draw. Some disagree, I know. On the other hand, if they mowed the affected area as rough, which most do, it just makes for an even harder chance to advance the ball.
Nothing wrong with a wide fairway where some of it is really of no use to you at all, whether blocked by trees, or too moundy to get a good lie, etc. However, with tight budgets, supers tend to eliminate as much fairway as they can, so that tempers the conceptually ok with some cost reality.
Conceptually again, the difference in the two examples is one you can advance forward, the other (get over sand lip but stay under overhanging trees combo) means you probably can't. Again, it might happen sometimes, and if natural, golfers might accept it once per round (if it happens to them) but if its clear the architect made it purposely happen that way, they have little tolerance for it.