I can understand your complaints. But syndication (the last S in RSS acronym) means exactly that. And that's what the protocol is intended for. Feed readers came later.
This is what syndication is for. I choose what to syndicate, to add value to my website. And you gain exposure from appearing on many different websites. That's why most publish just a teaser of each post and not the full body.
Again, I'm not arguing about what is right (or fair) and what is wrong. I'm just saying that the protocol has been developed for this use.
I like to include full feeds because it greatly improves the experience of people consuming my content.
I think we agree that stealing someone else's content and republishing it with your own ads is both legally and morally wrong. I don't see how publishing in RSS changes that.