Isn't it important to point out that this study was apparently centered around leg extensions? Conventional lifting knowledge and experience will tell you that bigger muscle groups (i.e., legs) respond better to higher loads. Maybe it's a kind of intuition that comes with experience, but if you've lifted long enough you get a pretty good feel for when you've hit a muscle group effectively.
Sure enough, it will take a lot more reps to feel the same strain on your legs as you feel from bench pressing. Arnold points this out in the New Modern Encyclopedia of Bodybuilding. He of course was picked on for his weak legs, but did manage to get some good size around the 1973 Mr. Olympia (Invalid Link Removed). He said that he found that leg growth required a lot of reps and sets -- up to 20 reps on heavy squats.
Long story short -- this article doesn't go against conventional wisdom, but it's important to remember that there ISN'T a magical formula for reps. The most important components are intensity, time under tension, and the motivation to push your lifts right to your limits.