Without going too far OT, it's a soft bag and is not meant to have a lot of structure, so that it can mold to your body. If you want a stiffer Evelyne you might want to see if they are still available in Madame or Epsom, etc. They don't tend to "lose shape" per se though.
Beyond that, it's really a matter of choice w/ an Evelyne - I don't usually worry about protecting the interior of unlined bags, and some people like/don't like seeing the insert through the perforations, especially if they wear the bag with the "H" outside.