I have to agree with the OP... from the picture those springs do make the back end look like it's sitting too low... almost as if you've got a couple of bags of cement (or a dead body) in the boot.
I know it's down to the shape of the bodywork that gives that impression - the arch on the front wing (fender if we're to be politically correct for our American cousins) being set higher to allow for bump/rebound clearance on turning the front wheels, but it is quite noticeable.