Solar domestic hot water makes tremendous economic sense, even on an individual level, unlike many things that make societal sense, but have a long payback period for the individual purchaser.  There are now many ways of providing freeze prevention to allow SDHW to work in colder climes.  This is a good general intro:
 http://www.backwoodshome.com/articles/hackleman65.html
With state and federal tax incentives - check out http://www.dsireusa.org/ - payback can be in as little as 2-3 years.  Even for more expensive, less efficient systems, payback in 5-7 years is a sound investment.  We just installed ours here in NC.  It's a batch design - more amenable to the sub-tropics like Florida, but I'm going to super insulate and we'll drain if/when we have to, but I doubt we will.  Anyway, both personally and societally, this is one of those simple early things we all can and should do to offset FF use.  Traditional water heaters often need replacement every 7-10 years anyway, so unless you've just replaced yours, you've got that expense coming up anyway.  Do a little research, and at the very least be prepared to go solar when the current one fails.  It's too late to pull it all together when you come home one night to no hot water and a mess in the basement.  Oh, and I concur with the tankless heater option - which in some cases can serve as your solar back-up.
Anyway, both personally and societally, this is one of those simple early things we all can and should do to offset FF use.  

You do realize that many of us rent, and therefore have no say in what kind of water heater or other appliances we use?

Yes, of course, never a good thing to generalize (all).  Just trying to encourage productive measures.  So much of folks reaction is of the deer in the headlights, helpless sort.  I'm just a doomer, trying to find those little things that may help on the way down.  But as you point out, the owner/renter barrier - just as the builder/buyer barrier - is a significant problem to making even the most logical energy improvments.
This is why my own "doomerosity" has a gradual upward trend also. As mentioned in another post, I rent a bitty apartment but the fridge is huge. The way the sink works, the only way to use warm water without scalding yourself is to have the water gushing at full stream. Oh, and the sink clogs if even a grain of rice falls down there or for no reason at all, so the garbag disposal has to be run, for a minute or so is best, whenever dishes are washed and periodically anyway. Air-drying laundry is  illegal here so when you do laundry, unless you keep it as secret as a pot-growing operation, indoors and hidden, you have to use the dryers as well as the washers in the laundry room. Doing your own gardening is likewise forbidden, there's the gardener, or one of 'em, who comes around with a poorly carbureted leaf blower and blows the leaves around. Sprinklers water the plants nightly, and most of the water runs off, taking soil nutrients with it - it's amazing anything grows the way the humus is cleaned away and the soil water-leached 365 nights a year. The apartments are heated by HUGE electrical heaters which I've never used, it's along one wall and I have storage shelves along there, so I use a small space heater when necessary. The stove is electric, thus ensuring one more highly ineffecient step (burn nat gas to make electricity to use in the stove here instead of just a gas stove). Needless to say the sink drips unless the taps are really shut off tight, and sometimes even then it does. Frankly, this place is almost designed to waste as much energy as possible under the circumstances.

Since at least a third, I think higher, of the population of the US are renters, mostly without the knowledge and awareness I have, to use compact fluorescent bulbs, a more effecient heater, etc., and almost all of which have the universal US household idol, the biggest TV possible, you can see what we're up against here.

Don't use the payback method and start using either discounted payback or a net present value equation to determine true cost.  You have to always keep the time value of money in mind.  It doesnt help that the petrodollar is crashing.