I'm not a lawyer... But, isn't it a legal issue?

My guess would be that the reason they're acting like they are, is that they have to strictly enforce the rules as they are written.

If they make exceptions or even approve an app that doesn't conform 100%; could that not later be used as a prior art opening up all sorts of discussions/legal-nastyness?

If they rephrased the rules such that they could use their own best judgement on a case-by-case basis, the discussions would just be bigger when one app gets approved and another one doesn't.

At least this way, it should be fairly clear as an app developer whether your app will get approved or not: If they can find anything "bad" in it, it won't.