Planning by nature tends to be about policy and strictly adhering to said policy, than the nuances of design. So something that should operate as an urbanistic guideline becomes a piece of policy that is wielded ruthlessly instead of being applied within the spirit of the law or on a block-wide basis.
Agreed, and this is a problem.
Precedent is one problematic issue here, the City is ever so concerned if they allow any variation in policy that the next developer will automatically go to the OLT and say "Developer A didn't have to, so why should I?"
There are multiple reasons why this problem (precedent) exists, and it's a function of a really broken system and the far too routine use of OLT (or any appeals body) that in some measure leaves staff hamstrung.
Of course, there is some wiggle room, which planners do use on rare occasion, but not often enough. But I'm not sure the culture is there (City Hall/Planning) to give planning staff a sense they can vary policy as often as they should.