The article should have provided additional parameters around which the selections were determined (unless you sampled only speakers that manufacturers were giving you for free in exchange for the review... though that would be nice to know). Price is probably the number one differentiation that consumers would consider. Then you have physical dimensions, power, inputs/outputs, and perhaps frequency response, which would be the collection of main factors that might categorize purchasing decisions...
...THG, you can be more comprehensive than this. You guys do Video Card reviews by price bracket and you're claiming sound is the big #2 sense used in computer use. You could do 2.0 speakers in two or three price brackets, 2.1 speakers in the same brackets and 5.1 or 7.1 in same brackets. We know you have the intelligence and enthusiasm