With the current iteration, the big change started in 2002. The big change was that the Chrétien government turned it from what had been a sleepy corner of the federal bureaucracy that was used by employers to bring in just a few thousand workers every year, mostly in the highly skilled, highly paid trades, as you said, technicians who had specialty skills that Canadians didn't have. They were coming in to install some products from Germany; the German technicians had to come in and out. It was used even for CEOs and high-flying accountants and professors.
That's what it was for, but in 2002 the government blew the doors off and said it would allow employers to use this program to bring in lower-skill workers, and then the skill level got lower and lower to the point that employers, especially in the service sector, were turning to it as a first choice for recruitment rather than a last choice, a last resort.
But the point is that what we're talking about here is something entirely different from the temporary foreign worker program.