The way you send it to another party is not standarized. Think in your grandpa, he would want to just create a transaction while everything else happens behind the scene. Sending an email is a manual process and you need to recheck if the other party received it.<p>Beyond this, there is a bigger reason: if you want a risk service like Sig3 or CryptoCorp you should adapt the system to every multisig wallet while if you have an standarized way to communicate you wrote an standard system.