I wasn't implying that we should all start using hidden APIs. Personally, I have a hard enough time using the documented API. My point was that a tool to catch such uses is pretty pointless, as it can be defeated using other entirely "legitimate" API calls.
To your second point, even apps that stick to using only documented API methods have known to fail after iPhone OS upgrades. So, let's not delude ourselves (or the users) into thinking we're writing robust (or worse, future proof) software simply by adhering to Apple's guidelines. All I would ask from Apple is that they get out of my way of getting an update to my users as quickly as I can.
To your second point, even apps that stick to using only documented API methods have known to fail after iPhone OS upgrades. So, let's not delude ourselves (or the users) into thinking we're writing robust (or worse, future proof) software simply by adhering to Apple's guidelines. All I would ask from Apple is that they get out of my way of getting an update to my users as quickly as I can.