I have a 6, see the jelly scroll (far overblown IMO, usually by people without one, who have only read about it in forums), and NEVER wish it was any thinner or lighter. It is already quite thin and light as is... already fits in a suit pocket and is also rugged enough to toss around.
To combat the jelly, slow blink during a rapid scroll or just look away for a second until the page is already scrolling. If I want to maximize the effect, I can focus on seeing it, but really: no big deal. Should Apple address it in the next generation? Of course!
A problem with always wanting "thinner & lighter" is the camera. While the tech guts could move toward being only a few millimeters thick, the camera must have enough depth for the physics of photography to work. 6 has already given up a flush camera. A thinner 7 would have to have much more camera bulge unless we want thinner at the expense of camera quality. There is no magical way to thin camera depth too to keep up with some march towards sheet of paper thin... which would also eventually sacrifice that "rugged" goal too.