Yes. Coke, McDonalds, The Gap and every other consumer company try like hell to create involuntary behaviors in people all the time.

is it ethical to judge users for behaviours deliberately created in them by applications?

Yes. Other than the specificity of the words "by applications", this is what credit scores are designed to do. Madison Avenue in deliberately trying to create behaviors in all of us. A credit rating measures a person's ability to resist that when it isn't financially sound.

should the attention of users be better protected?

No, at least not for adults of sound mind. People are free to make their own decisions, whether that's doing a keg stand or spending 3 hours clicking a button on Farmville. People can be warned about potential dangers, but it probably won't have much of an effect.

can we start developing consumer applications that aren't deliberately designed to capitalise on the attention of their users?

Yes. Or at least, you and anyone else who wants to can. But making products that people use frequently is a common definition of success. Most comapnies aren't going to pass that up because some people have addictive personalities.

how can we educate people to navigate a world of applications designed to hold and capitalise on their attention?

Good luck with that. Education vs the Forces of Capitalism. Winner: Capitalism.