While I don't have experience as you do, I was going to say that I suspect it is not for money. Once installed a fountain requires very little in the way of maintenance. Top up the water every so often if it needs it, clean out the skimmer, and maybe throw a handfull of mosquito granuales in it every so often. Once it a while you do have to scrub the thing out, but it is still not a big deal (that is what I do with the one my yard).
Comparing that to the time and money I spend on flower beds and planters - I would rather have a yard full of fountains. Of course they cost a lot to install in the first place.
I am guessing it is water quality as well - who knows what people put in the fountains. But then again, when WDW maintenance was at a high point you got the impression - just walking around property - that it was a nice place, and you should treat it as such. Now, it seems like an upscale Six Flags - and people treat it as such. I'm not saying it is right, but people tend to act as you expect them to act. You behave differntly in Cosmic Ray's than you do in Victoria and Alberts because you expect to. Maybe if WDW expected it's guests to respect the park because TDO respects the park, then guest would respect the park.
-dave