JKM,
Probably some of both.
I can recall an architect elimating a unique feature because he feared that some idiot would ride his cart up on its gentle side and crash off its steeper side. Legal issues seem to mute or eliminate quirky architecture.
Architecture that's interesting and/or challenging, that slows down pace of play is often eliminated, be it deep bunkers or other features.
Environmental constraints have and will continue to have a substantive effect. Water hazards, have to be given a wide birth, removing them from close play. That's certainly a factor in dumbing down the architecture
I've heard so many people, especially on this site, including the "Emporer" Tommy Naccarato, complain about Sandpines, and the perceived dumbing down of the architecture. Ted Robinson's courses were panned as well as many others.
Steve Shaffer,
Just today someone brought up Twisted Dunes, which I liked, but, others have stated that its a manufactured course, unnatural and contrived.
If anything, I liked its quirkiness.