WhiteKnight,
When you are tracking down on a final approach with a crosswind then if you don't use the sideslip approach then what is happening?? You are crabbing into the wind right.
Same thing occurs during takeoff - as soon as the aircraft becomes airborne then it will want to crab into the wind and then some extra drift is layed off by steering a few degrees left or right to prevent drifting over the ground.
Now if you take off in a C152 then you will experience a lot of weathercocking because the aircraft is slow but less weathercocking will be experienced if your take off is in a 747 because there a lot faster and the wind will have less influence on a faster craft because most if not all of the wind it experiences is from itself......only a small amount of drift has to be laid of in faster aircraft.