Monza was once paired with other ultra high-speed tracks that demanded a low-drag set-up.
With these other tracked being sanitised or dropped from the calendar, Monza now sits alone as the home of high speed in F1, just as Monaco represents the classic low-speed street circuit.
Thus, the set-up seen on the cars is unique to Monza, the teams having to develop parts especially for this race. Many parts are developments from previous wing designs and hence are not totally new, but the cost of developing a package for one race are not in keeping with F1's current cost-cutting mentality.
Fortunately, some of the changes to the cars are as simple as removing parts fitted at other races to improve downforce. So the proliferation of winglets, tabs and fins are taken off and the F1 cars look a lot better for their new simplicity.