The title is trite, I know. But the underlying point is something that people generally have a hard time wrapping their heads around.
Applications before the Zoning Board of Appeals, the body that grants variances from the Zoning Regulations, almost always center on whether the neighbors like the people who are asking for the variance. Except the people requesting the variance are human. They are mortal, which means they will eventually no longer own the property and others, perhaps others who are less friendly, will eventually be the beneficiaries of the bending of the rules.
So, before you think it is fine that the neighbors' garage can be 5' from your property line, it might be worth asking if this would always be okay. Since it will now be that way forever.
Likewise, uses approved by the Zoning Commission for specific locations are approved forever. Once a *use* has been approved, the specific tenant or owner can change and almost certainly will. Everyone might be wildly enthusiastic about a high-profile tenant asking to move into a location. But retail, or restaurant or service businesses are hard to run profitably, particularly in the internet age. And once a use is a approved, the tenant could leave tomorrow, and someone else could be there with a less appealing version of the same use.
All of this is not to say that you should not care about the qualities of a particular neighbor. My first question to almost every possible applicant is "have you talked with your neighbors yet?" Good communication is really important. But neighbors will come and go. Land use permits are forever.