How many homephones do you know ...
that wirelessly connect to a predefined external device (such as a watch) to show the caller-ID if somebody calls in. Without such a phone, it wouldn't work.
Now imagine you have such a watch and your partner has such a watch also. Then the homephone would either have to use some broadcast protocol or be able to connect to 2 different watches at the same time.
With many different home phone makers and even more watchmakers, this seems to call for some IEEE standard before anyone would even consider making either a watch or a phone that does it.