I'm happy I'm currently in the middle of my PhD, but this article makes a bunch of errors. It generally strikes me as the naive impression that undergrad have of grad school until they spend some time talking to post-doc and professors. I'll just identify a couple of obvious ones.
1. "We all read the PhD Comics and we all hear about how many hours of coursework or admin-duties a typical US grad student has. I don’t know how does it look like in other countries, but in Norway, Denmark, Holland and Belgium this is definitely not the case. "
The Economist article doesn't say anything about there being too much non-research work. It says there are very long hours, and part of it is non-research. The OP has simply misinterpreted the Economist article. I don't know any grad students in the US who spend more than 25% time on teaching, and the OP lists this maximum as some sort of great aspect of the Nordic system.
2. "Apart from all that, a little bit of teaching looks good in your CV, especially if you want to apply for post-doc or other academic positions after finishing a PhD."
For most grad students, than this is just plain wrong. No one cares how good of a teacher you are (especially not for post-doc positions) unless your end goal is a teaching position at a small liberal arts college. But most most grad student's end goals are either research positions or industry.