There's a difference between being crowded and inefficient/slow (North America), and being crowded yet efficient (Europe/Asia). The Yonge line is pretty packed during the rush hours, but I still get to my destination on time provided that there is no delay along the way. That, I don't mind.
But if we're spending millions and millions of dollars on a part of a subway line that won't get used, then what a waste. People were laughing at Sheppard when the subway was built there, but this will be the ultimate joke in comparison. At least Sheppard gets its fair amount of use during certain hours of the day.
So, I'm all for crowded lines, because all that will mean is that the cost was justified and then you talk about moving on to the next step.