If someone breaks into my home and hacks into my Mac (using the OS X DVD to do a password reset), I have a lot more worries than whether they know how to find out what neighborhoods cell towers Ive used! Luckily, encrypting your iPhone backup is simple, automatic, and unbreakable; and has the added benefit that then your iPhones keychain gets included in the backup. (Otherwise it doesnt, with good reason.)
If, on the other hand, they steal my phone, theyre unlikely to stop me from remotely shredding it so fast their head spins
That said, dumping the old cached data is good practice, and Apple really needs to do so. Id be surprised if they didnt patch it to do just that. So: good catch! (Of course, this was noticed months ago.)