I don't really understand the comparison here. Lots of people are very frustrated with slow zones or other limitations on line 1. They don't suggest rebuilding line 1 because that is obviously not the solution to the problem, maintenance and modernization is, and that is clearly on the long-term agenda!
Even with theoretically perfect operation and maintenance there are non-trivial capacity and speed limitations to road median tramways that grade separation potentially addresses. Whether you think that eventually will/should happen is another thing that I don't really care to argue about, but it's clearly not unorthodox. The first ttc subways were themselves built to replace streetcar lines. And the SSE most recently was always premised on ripping up the RT. Transit infrastructure is often iterative, this seems rather uncontroversial to me