Why we still come home in the water
Runways look modern. The ocean is the safer answer, and we will take safer over modern every time.
People ask why a vehicle this advanced lands under parachutes in the sea like it is 1969. The honest answer is that the ocean is forgiving and concrete is not, and forgiving is the entire design philosophy of a crewed capsule.
The water does work for free
A splashdown lets the vehicle shed its last energy into a medium that yields. A runway landing asks the vehicle to be a working aircraft at the end of the worst thermal event of its life, with no second attempt. We would rather spend that complexity budget on the heat shield and the parachutes, the two things between the crew and a bad day.
A box one kilometer wide
The trade is precision. We have to put the capsule inside a one-kilometer box so the recovery ship is already there when it arrives. We have made that landing forty-three times and the ship has been on station forty-three times. Modern is not the goal. Boring, repeatable, and exactly where we said it would be: that is the goal.