Maybe you should try a few (also paid) plugins, before generalizing. I agree with you about the one mentioned above. I also agree that in most cases, it's not necessary to protect your content.

But there are also situations (membership-sites) where you got really valuable content or images and it's important to prevent or at least make it harder for people to copy and publish it anywhere else.

The majority of content thieves are persons who simply copy and paste your text to other platforms like forums, social-sites, free blogs. So by making it harder, they will think about it twice to search in the source code and put so much effort into it.

However I just viewed at all the wp content protect plugins and the ones that seem to be very solid and useful are these two:

http://codecanyon.net/item/wp-control-copy-protect-content-serve-copy/4289952
http://codecanyon.net/item/smart-content-protector-pro-wp-copy-protection/5400835

I will try to test them within the next days, if someone is interested, I can also post a short review.