The main reason why CCS needed the extra pins is because they needed the socket to have backwards compatibility with the Type 1 (J1772) / Type 2 (Mennekes) AC connectors and the pins and wiring was designed for 80A (140A for Mennekes plug when going through 4 pins as in DC-mid mode). Yes, Tesla was able to get 370A through the same sized pins (in Europe; the US version actually has power pins the same size as CHAdeMO), but they played tricks in regards to insulation and charge tapering to get there. However, CCS being an open standard must to designed to be easily manufactured by a wide range of manufacturers and still be safe, so that is how it ends up. CHAdeMO on the other hand was designed like a gas pump nozzle (including a lever) and was originally designed for commercial use, so that is what carries over. The newer versions have slimmed down the design significantly, but the socket makes it so there is only so much you can do. Personally my order of preference is Tesla > CCS > CHAdeMO.