That is part of it yes. I might miss a call from someone driving home and would rather contact them on their home phone later on, ect. The other part is streamlining your replying to sms and calls.(ignore the girl on the top, she was there to make you look)

Once you click on a message you are presented with the option to reply right away, or you can select the other options from the bottom. It gives you more flexibility than you have now (linked to your address book), less clicks to get where you may be going (one click reply to text), and still keeps the options to dial or cancel. You can use the same interface in the recent calls list as well, keeping all the functionality and making it a little more streamlined.