Bag lady?

I seem to have so many plans for new bags of various sizes and shapes that I'd better be careful or I'll get a new nickname...

The new bag is taking shape, though. The quilting took a while, but was fun. Once I started working from the pattern, though, that changed. I seem uncapable of sticking to a pattern - I always start thinking of other ways to do things, and before you know it I have stitched myself into a corner. There just might be a reason for the designer's suggested method of making it, I guess, but somehow I always end up trying my way first, or thinking that there must be something wrong with the pattern... The main problem with this one though, is the thickness of the interfacing/batting - broken needles, bent pins and quite a few scratches to my poor fingers are included in the making of this bag.
I just managed to get the bag itself ready before I left on my weekend trip, and today I have stitched the lining together and I just ad to pin it inside, to see what it will look like. I will have to take it out and press the seams, of course, and I'm also adding something the pattern does not include: an inside pocket with a zipper and an extra pocket for my cell phone.
I don't see why the pattern calls for stitching the binding to the top edge first and then handstitching the lining in after. To my mind it seems a much better idea to sew the lining, bag and binding strip in one go and just hand-stitching the binding to the inside? But I will read the pattern once more - there might be a good reason for this approach...