The movement of a 5959 is made intentionally as small as possible, and that increases the care which must be made for that center pinion. I'm not at all saying that it is simple to make a piece like that, look at all the problems the 5004 had when it originally came out. On the other hand that's not an issue of "complexity", it is an issue of care in industrial design, good metalurgy and tight tolerances in manufacture and QA.
Compare the 5959 to the rattapante module that f. piguet uses on the 1185 and similar, which has been in production for at least 15 years. It uses a classic column-wheel design, and adds approx $10k to retail pricing of a watch. That implies not a very high degree of complexity, compared to the original cost of the 1185.
A