another reason to not like it: if there are out there ciphers which could be broken with such hypotetic tecnique we miss the chance to move away from them/design ciphers that are robust against that tecnique. which is exactly what secret services usually want to have a cryptographic advantage over enemies, but at the same time they endanger everyone else, as also the enemy coukd independently discover that tecnique and start using that against e.g. businesses.