We used to produce and sell everything here in Canada, and while 'free trade' has been good for us generally, it has quite obviously also created vulnerabilities, as we now find out with one monolithic and dysfunctional trading partner.  We need to restore some balance in terms of manufacturing capability.  Keeping the dollar high (under Harper) has also hurt the manufacturing based economy of eastern Canada.
Most importantly, we're missing out on secondary processing of lumber, beef, petrochemicals that would create and keep jobs in Canada.  I think 'free trade' is still the way to go, but we have to be much more intelligent in how we manage it.