Alvin,
While you are right in an ideal case, I fear that Toronto's post-1970 history of central planning has been blindsided by embarking on projects for political gain rather than public need. Until we reach that critical point where congestion is unbearable along certain corridors, and too hard for even the most oblivious politicians to ignore, we will continue to have hare-brained projects like the subway to Vaughan over useful additions to the network. Cities like HK, Bangkok or Taipei had to reach that critical point in traffic congestion where walking anywhere is pretty much faster at all times of the day, to invest in rapid transit systems. But these are excellent, comprehensive rapid transit systems when they were built, serving people rather than cornfields. The same was true of the momentum behind the construction of subway systems in New York or Paris a century ago.
For this reason, I support hyperdevelopment of areas that are already beyond transit capacity, but where people might actually want to live. Further development of the King street west corridor, despite the fact that streetcars cannot keep pace with what is being built right now, is a good example. It might just spur the construction of something like a DRL once the congestion along that street has reached the tipping point.
I know it's like putting the cart before the horse, but sometimes that's the only way these things get done.