This isn't a case of PayPal acting in a predatory manner, but of people taking advantage of one of the PayPal features where you can request money from anyone with an email address. While it's great that there's an easy way to do this, it means that it's also easy for spammers and scammers to attempt to take advantage of you.
Getting an email that says "so and so sent you a money request" is not in itself a danger - and it does not mean your PayPal account has been compromised. There are two risks involved though...
I recently got an email (a legitimate one from PayPal) saying "ART SOFT DIVULGAÇÕES sent you a money request" for the amount of $7.86. The first give away was that it was in another language and I'm sure I haven't recently done any business with anyone overseas. When I logged in to my PayPal account, I could see the requested transaction there, so I knew it wasn't just a fake email.
If you get a request like this, the best thing to do is to log in and go to your summary or activity page, find the request, and click "cancel" underneath it. This is better than leaving it there, to prevent any future confusion or accidental payment.
As always, the rule of thumb for any email you weren't fully expecting is to be paranoid and suspicious, almost to the point of covering your keyboard in tinfoil. (Maybe not quite that much.)