Completely agree, it's what's best suited to the app. being created.
I'd use Access (spit!) for certain things, but not for a serious app/site/amount of data.
I wouldn't expect to see the MUCK approach in a serious project, certainly not in a commercial project (though I have, and it did cause hideous problems).
For personal usage or a small group who understand the implications of what's being done it's fine.
But the problem is, these things often creep into production, or worse still, get taken as an acceptable example by people who don't know any better.
I think the main argument for always doing it the right way is that if the DBA can't be bothered to do it right on EVERY occasion, some developers will see it as an excuse for them to go down the same route, even though they may not understand the implications of doing so.
All comes down to education - the old saying 'A little knowledge is a dangerous thing' is probably most apt here...