Canada beats the US in both percentage of foreign-born and net migration rate
This includes all immigration. I was specifically talking about skilled immigration.
Even then, some of us value the safety of the whole city, not just a tiny neighborhood. Also many immigrants will value the outlook for their kids, not just for themselves. Maybe they have a high paying job, but what about their kids? That's where the average or median lifestyle comes into play. Even if being from a rich family helps, you can't be sure that your children or grandchildren won't live in poverty.
You can't be sure, but you can give them a significant head start in form of a good education and a solid starting capital, which helps a great deal. Ultimately, it's a lot like stock market investments... you can go for low-risk and low-yield, or you can go for high-risk and high-yield. Both are viable strategies.
(And, of course, you can always go high-risk for yourself, cash in on that if your bet pays, then move to some other place to spend that money. And getting a citizenship in a first-world country makes it much easier - it's easy for an American citizen to move to e.g. Canada.)
In any case, yes, there are many choices, and people do choose differently. I and many of my friends picked US for all the reasons that I've described; I lived in Canada, as well. I have friends who have settled in Canada, and other friends who had Canadian permanent residence, but moved to US when they won the green card lottery. I also have some in Australia.
Bottom line is, to answer your original question: US is still a very popular destination for skilled immigration, enough so that it can certainly get more people coming in if it makes the process easier to avoid being out-competed by Canada and others.