So, what I understand is that hidden services can easily be deanonymized. People using tor only as a proxy are safe, provided they do not download big files (who want to do that anyway, given how slow it is?).

As a Tor user, I'm quite glad to read that, actually. Tor hidden services are the reason why Tor has this ugly and well-deserved reputation of being a tool for everything illegal and morally unacceptable. As someone who just want strong privacy, I see hidden services as problematic neighbors and I would be glad to see them go.