Although he would rather let his younger sibling shave him bald then admit it, Itachi had always been rather anxious about meeting his soulmate. There were speculations that the Meters were a product of generations long ago, back in olden times when carrying hidden weapons was typical and being a ninja was a common profession. Back then it would have been

useful

to know how dangerous one 's soulmate was; it might have actually helped you find them. Nowadays the Meters were largely superfluous, only helpful if one by chance happened to stumble across one 's soulmate and touch them.