Jim, like you, I have started to give a low rez file for each print bought. I make it 500x500 save it at level 7 and oversharpen *just* a touch. It looks good on a website, but will print horribly. I do so because people ARE going to scan them and put them up anyhow. You can try and stop them, but it just gets you frustrated and mad at the world.
I had someone excitedly tell me that my photo was in one of the yearbooks. I decided I just wasn't going to be upset about it. I know they ordered from me and I am going to look at it as excellent advertising. I do ask that when using my photo on a website, they link back to me. Some do, some don't. So I stamp them with my web addy.
I do think the world has changed. It was much harder to steal a photo before it could be scanned and printed on a home printer. The internet has made people TRULY believe that if it is on the internet, it is free. I had someone ask me if I would print a photo for them for that reason. That on the internet made it public property. Of course they got an earful but, I am sure they ignored me
I don't really care if my stuff is used on personal site. I do care if it is used in advertising. That is the line I draw at.
But Jim, I think you are right. Photographers are going to have to change with the times to a degree. Theft is a matter of fact and people make no apologies for it