Well actually you can tell all your current friends, and yeah when a new friend adds you as a contact you can tell them also. Like i tell my daughters, there is nothing you CAN'T do.
Besides that, I am assuming the point you were trying to make is that this is an inconvenience? Well, as I stated, this is not Apple's responsibility, and it is no different than changing your email address, phone number, or physical address. If you change this information, it is up to you to contact people who might be trying to contact you.
My wife moved in with me last year, and filed a change of address with the Post Office, and when trying to do her taxes this year we didnt receive her W2's because the IRS did not have the updated address, and the post office does not forward these, just rejects them. We had to contact the IRS to get this updated and sent to us. Inconvenient yes, but do people file lawsuits for this?
People really need to get over themselves, is missing messages really such a big deal? what if phones didnt exist how would you communicate? And there are plenty of other reliability issues with text messages, if they are so important to your life, you really should find a different form of communication... ie actually calling someone which is more reliable, or if you really want to be sure there are no reliability issues, then talk face to face... of course then you have to deal with the other persons reliability, and they may not be listening. **** there is another stupid lawsuit like this one, when someone says a phrase that is no longer used and i no longer remember the meaning, that message is failed to be delivered, who do i sue for not informing them that i cant be reached with those words?