Yup, what's even worse is when the factory plastic (insulated) intake tube is replaced with a shiny aluminum one that just sucks up heat from the engine bay.
If its bigger, I can understand, but a lot of them aren't.
One thing not mentioned is the ability to change filter geometry though. There are some kits out there that utilize the factory intake plumbing (bringing in air from outside/grill) and replace the factory "box" with one that can hold a cone filter instead of square. The article said they used a cylindrical filter, but doesn't show what kind or if there are any differences.
Its also a little sloppy with its labeling (what particle size were they using for filtration efficacy, graphs, etc) , and their stand-alone tests don't exactly jive with their vehicle performance tests.
Note they don't mention the parameters for the test (0-100 km/h?) unless I missed it.
They mentioned the real world filtration of the K&N is likely much better than what they reported, but don't go into too much detail why other than "more of the filter would be used" or something.
For the graphs you posted relating to pressure drop, it would be good if they continued the graph beyond the 3500 RPM to have better separation between the groups. The OE filter shows about 1.55 kPa vs what... 1.85 kPa for the K&N? That's extremely negligible (0.043 psi for the people out there using freedom units), and within the realm of equipment error (which they even mentioned is entirely possible, given that they put the meter in the elbow of the intake and are likely picking up turbulence).
Ultimately I think there's better studies/reports out there.