The one thing I like about texting is you can respond when you want to or have time. Not like a phone conversation that you have to engage in right then and there. I will have conversations all day long with someone through texting.
That's the only thing I can think of right now. My BF hates it when I text. He says - just pick up the darn phone and call her!!! LOL

ETA: What you said is a good one. You can send someone a message to call you when they cannot be bothered with a phone call. Like when you know they are in a meeting or school.