Just some of my ideas. Leave your ideas in the comments.
We could save text. We could have colored text as long as we have access to the colors. We didn't have to mask to change the color of something. We could save frame layouts. We could share elements, which use theme pack elements, to others that have the same theme pack elements. We could Inbox elements to friends, so that we don't have to publically share the elements. We could have frames that aren't square. We could have a 3 row option. We could rearrange elements to our liking. We could combine booklets like chapters in a book.
There are so many other features I could think of that would make Strip Generator a whole lot better.