Looking at the article, it looks like the hard shell "urban" helmets are just not performing as well as the big blocks o' foam. Several years ago motorcyclist did a study of motorcycle helmets and had a similar result. The soft bulky helmets do perform better in single "hit" tests.

However, unlike motorcycle helmets, bicycle helmets are, generally, not mandated. So, it becomes harder to make a real comment on the overall effectiveness. If a rider is willing to wear their Nutcase (picked because it was named in the article) on 99% of their rides, versus a block 'o foam for, say, 20% of their riding, are they better off with a Nutcase or a block o' foam?

You are probably best off with a full face motorcycles helmet; however, you probably wouldn't wear one. I remember a question being asked about motorcycle gear, "if you knew you were going to be in a crash on a particular day, what gear would you wear? To me to obvious answer was, "I'd stay home that day."

It is all about compromise; however, that does not say that these testes are unimportant, or should be discounted. To make compromises it is best to be as informed as possible. Myself, I think a person is better protected by wearing their Bern (also named in the article) on 99.9% of their rides instead of only wearing their block o' foam on their weekend group rides.