I've used this pattern and I love your modification! This bag is super stretchy and fabric handles would give it more strength.Thank-you! I actually made several other mods to this pattern, probably so many I could call it my own now. Besides the handles, I made it wider and shorter so it doesn't stretch down 3 feet when you put stuff in it. I took the one in this post apart and redid it with the improvements after I saw what it looked like with something in it, I was horrified and would not have asked my worst enemy to use it! It's all good now though, much nicer!
I'll have to do that to the next one that I make beacuse I get the strangest looks walkin' out of the grocery store almost dragging my groceries along the ground.