Getting an accurate portrait of Canada as a whole is very difficult, as healthcare is a provincial responsibility.
As a Canadian however, it would not surprise me if most of the people traveling were upper class people trying to bypass the waiting lists.
You have to understand that this is inevitable as long as our systems don't have the same level of fairness and people are allowed to "choose" their system. Of course privileged people will choose the system that they can benefit from most, whereas unprivileged people cannot afford to choose.
This is not to say that our Canadian healthcare systems are perfect (far from it), but rather that some of them attempt to promote fairness (in service quality and rapidity), thereby negating the greater privilege of wealth relative to less fair systems such as yours.
This practice of healthcare tourism does of course take some pressure off the system for unprivileged people, so it's hard to say it's all bad on the whole. But don't expect the situation to change regardless, as we are also ruled by the wealthy, and they do so like to have freedom of choice.
By the way, the position on the waiting list is often adjusted according to the urgency of one's situation, so people who travel to reduce waiting time would not have been in critical condition on average, not to mention they may simply be traveling to get services that are legislated differently in Canada (as I believe cosmetic surgery can be, depending on the province).