To some extent I believe many Torontonians still believe Toronto outside the CBD and Yonge corridor should still remain the quaint Collingwood sort of small town feel, and anything taller than say 8 stories are "destroying" the tranquility and character of those low-rise neighbourhoods in the middle of Canada's largest city. This is why a 24s apartment at College/Spadian or a 25s cond at King/Church could be considered too tall (among other reasons, but most related to being too tall - the ubiquitous "shadowing" issue, or noise/congestion problem).
Protecting heritage is paramount in city building, but often it is just a disguise. I fail to see approval of a highrise will threaten heritage by setting "precedent" - aren't heritage buildings protected? The precendent only serves the good purpose for the city to be able to replace more 2 story slabs in downtown with something more dense and meaningful. A brand new 2 story pharmacy at this location only shows how backward and provincial-minded we are - because apparently a ten story is considered too dense for this location?
The Rexall isn't a new building, just a recently opened store in an older building that was previously a a computer store and orginally a bank.
Some people I guess would want to build tall for the sake of building tall, perhaps saving designated or listed heritage buildings.