But you can use email to send a text message to anyone's phone, and any text message can be sent to your email address. I guess I don't understand the problem. Sorry.
I put your number in my phone. Now I can text you. If I have to e-mail, then I've got to put your email in there, too, and take the extra time to select your e-mail address when I send a text -- if I remember, which I probably won't if I'm in a hurry or in the middle of something else, which I usually am if I am texting.
And what deb said, which I didn't think about, not using the web features on my own phone and not living in some backwater third-world city...