Look, there are already people who put lifts in their kids shoes, sneak kids into lines or go behind CM's backs. The current system doesn't stop them. So yes, these same people can look for the "hack" to swap the band. The overwhelming majority of people would be using this system to prove their kid is tall enough. But, let's just say the parents swap the band, as long as Disney also incorporates a waiver system, they will be liable for any harm to their kid. As of now the burden is very murky with CMs in charge with non-universal measuring.And yet I have an intact one sitting on my dresser. It is no where near impossible to get one off. Fairly easy in fact.
If the current system doesn't stop the cheaters, why not make the system more friendly to kids who are tall enough? In the end, cheaters will cheat. But "of height" kids shouldn't have to suffer because of them.