I use Messenger Bags because I find that they are more comfortable and accessible to use. I'm certainly going to get a backpack for my Macbook Pro, but I'm not planning to take it wherever I go. Thus, I'm looking for an air as an ultra-portable solution for my messenger bag so that I have a laptop on hand wherever I go and whenever I need it.
Sounds like you need a better messenger bag with a wider shoulder strap and a decent shoulder pad to spread the weight?