Hi there, I know I'm going to get in trouble for saying this from many on the forum but here's why:
1) Developers will take too long to propose something really tall and in turn may miss the chance to build something because by the time they get to it, the economics might have soured or there will be few to no sites to develop such tall buildings (of course they can justify that by citing US, Ireland and Spain as examples of what goes wrong when you're too ambitious, and that's true but if not in these market conditions - Toronto's conditions are great, so if not now, then when???). And the developers will be too conservative in other ways - focusing on maximizing the bottom line by having projects that are simple boxes they know will sell. It's the downside of a strong market.
2) Toronto's silly laws/regulations/policies, etc. will continue to ensure that we always remain less-than-optimal in virtually all contexts. Case in point - the Tridel 75 storey tower where a city official said that building has to be in line with its surroundings (i.e. boxes), forcing Rudy Wallman to change the design, so even when there's a chance we can get a different looking tall building (i.e. flatiron), we won't be able to utilize that potential.
3) The tall buildings study, which I think is mostly - not completely - unfortunate, and NIMBYism will also affect other sites in the greater downtown area, which will result in shorter than potential (and probably boring looking buildings).
At the end of the day, Toronto is like a B+ city...it'll remain strong, healthy, diversified, energetic, etc. but it'll continue to have this underlying tone of not meeting its potential and therefore the pessimists will continue to say oh I wish Toronto was like this or that city and the Toronto-blind-defenders will come back and personally attack those people by saying things like "if you don't like it here, why don't you move to city XXX" without realizing that it's not always possible to literally move to another city in another country so easily. And while constructive-criticism is fair, it won't be accepted by many on this forum.
How's that for a candid explanation on why........