I think sometimes communities, or to be exact, some individuals in a community, don't know why they are offended by a development. They just react on some visceral level and then seek some way to rationalize their objections.
The backlash in Centretown seems mostly to be caused by the attempt to rebrand the neighbourhood as "South Central". Some of these residents obviously have a deep attachment to their neighbourhood and somehow feel it's being taken away from them.
It is a clumsy rebranding attempt and the developer only makes it worse when they say they've consulted some local businesses and got their ok. Local businesses are part of the community, but they are only part of it. There are church, sports, social organizations that feel they are the community and they can rightly wonder why they weren't consulted. The developers would have been smart to work with them, funding a couple of youth sports teams or existing community event, organizing a food drive, etc. It's simple stuff, but it shows that you want to be part of the community rather than just draw a line around a couple of blocks on a map an market it.
So it's a public relations blunder to begin with, and it stirs up wrong headed protests like this.