I think Wendall Cox is a Croc! He has a some sort of personal vendetta against Portland, OR, which I dont get. His website mentions how Portland has such a low population density and horrible traffic problem. He also mentions that Los Angeles, California is the model city. Just because a city has a low population density, it doesn't mean that it can't be an effective city, and vice versa.
I lived in downtown Portland, Oregon for 6 months, and despite it's low population density, I feel it is a very pedistrian friendly and convenient place to live. On the flip side, there are areas in Honolulu, Hawaii with really high densities, but with barely any foot traffic. Again I must point out, more density doesn't always equate to a better city. There are many more factors that contribute to a cities prosperity. As for the traffic in Portland, Oregon-it wasn't half as bad as it is here in Honolulu, Hawaii. And if the traffic were bad in Portland, it really wouldn't of mattered much, as I rarely drove. As for Hawaii, a car is almost a neccessity.
He also mentions that most light rail systems are a waste of money, and rarely anyone uses it. Nonsense! Although light-rail isn't as quick or convinent as mass-transit, it is heaps more better than catching a bus. Ridership on the MAX and Street Car was high from what I observed. It was like riding a ride at Disneyland. You also can't forget the fact that the emissions of the a light-rail system is cleaner than what busses emit.
Don't take Wendall Cox word for it, and visit Portland, Oregon. It's a great city, with many great attractions within walking distance.