I think it should be up to the individual courses (and it is, for the most part).
If you want to join a more "strict" set of dress code type club, then join that. If you want a more relaxed atmosphere, join a club that allows for that.
And if you join one or the other...adhere to it. You should know their rules regarding dress before you join. And if you don't like it, FIND A NEW ONE.
I personally have no problem with what anyone chooses to wear.
I've played some courses that are pretty strict; and I've played some courses that are more relaxed.
I have no problem with either. I actually like wearing polos when golfing. I prefer to wear khaki shorts (in summer, when its humid), but I am ok with khaki pants.
I do tend to enjoy the looser atmosphere more though. I like talking to people. At the course I've spent most of my summer golfing this summer (last summer was more of a "yuppie" type atmosphere in comparison)...its looser.
I've had people approach me, talk to me. I've been offered a beer. I've heard roars of happiness on good shots. And yes, I've had my golf ball roll through some unfortunate ball marks on the green.
And I am ok with that. I love golfing; but I also love encountering the different people on this course....rather than the same, old, stiff people that I usually encountered last summer.
And for whomever complained about sandals...
I spent $70 on my footjoy sandals. I'm wearing them. Yuppie course or not.
:)