Indeed. Quite an interesting question given that the prevailing mandate of the planning profession in Ontario is to serve the public interest.
Is that public interest set forth by City Council? I would immediately wonder who is being excluded from that conversation and is not a part of said public interest. There is the usual disenfranchised population groups to speak for, but I would also be concerned about the Ontario that today's youth will one day inherit when they become of voting age, as well as the interests of future residents who may decide to migrate to this region from elsewhere in Canada or abroad at some future date. Both population groups have zero say on what municipal planning policy should look like, but will constitute the majority of tomorrow's residents and will inherit the consequences of decades of entrenched homeowner interests on their future communities (as we see playing out with the housing market across the region). The directions of City Council seems like an inadequate way to ensure that all stakeholders are accounted for in planning policy decisions that involve a longer term time-horizon extending beyond the next election cycle.
Of course, those non-electorate stakeholders (who might not know that they are stakeholders) can't be expected to have a meaningful contribution to planning decisions being made today. This is where I would personally place onus on the planning profession to consider those interests when making decisions at the site-specific level (e.g. delivering affordable housing, ensuring representative community consultation, considering if children have a place to play in the neighbourhood), as well as at the macro-level (e.g. actively planning for how projected population growth targets can be accommodated in the municipality, not embroiling future generations of residents with substantial infrastructure investment deficits). It is also worth pondering about the situation where two representative levels of government clash on public policy, as is the case when a municipality proposes a secondary plan limiting growth around a major transit station area, in contradiction to prevailing provincial planning policy.
However, as you rightly point out, it is difficult to expect that the municipal planning staff contradict the directions of council. They are staff after all, and tasked with serving the interests and whims of council. I suppose this all to say, that I believe there are some serious problems with the way we do planning in Ontario, especially when it comes to long-term planning of land-use and growth. I'm not sure how much more bold you can expect the municipal planning staff to be, but I do believe that we collectively have to be bolder as a region to meet the challenges of growth, mobility, and inequality before us (which unfortunately, probably falls to the leadership of our elected officials...).