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.Yes. In my opinion, the connector doesn't need to be as large as it is - whether J1772-DC or EU CCS. The adapted type 2 connector (and the TSL02 in the US) are both far more elegant than the frankenplugs (whether J1772-DC or EU CCS).
There are also some psychological reasons for this as well -- the perception is that the bigger the connector, the more anxious and nervous people will be in using it - it's scary and dangerous when it's a bigger connector! Just as a simple example, my wife has no problems whatsoever plugging in the TSL02 at home and she does it daily. Ask her to plug the CHAdeMO connector from the level 3 station into the CHAdeMO adapter? "You can do it."
This makes a big difference for a good amount of the driving public, and will be a big issue for Model X users.
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.