Why would anyone spend even 1 second developing for a platform where someone could yank the rug from under you like that.
Because you get a set of rules that you have to stick to, and if you do, the app will be published as many, many apps demonstrate. If I recall correctly, one of the app requirements is sandboxing, and grabbing data of other apps is per definition in conflict with that (at which point it may flag already as non-benign).
In addition, if I were a malware developer I'd LOVE to have a tool that allows me to check that my malicious code is well hidden from Apple evaluation. I'm surprised the developer cannot see why Apple would have a problem with an app that makes testing that possible.
It's not really as black and white as the developer makes it out to be.