Simple answer, is because wing down is easier to maintain stability right down to touching the ground.
Objectively I find it to be more difficult to sideslip down final than fly controls neutral pointed into wind.....but of course you may find your method easier.
Alternative is having to use a boot full of rudder at the last moment, then sudden use of aileron to stop the wind blowing you side ways when you straighten up.
I have literally flown tens of thousands of approaches and never ever had any difficulty using rudder to align the airplane with the runway with co-ordinated into wind aileron as needed to land.
Larger aircraft have more momentum, meaning they are less prone to being pushed sideways in the wind once you straighten. Also some large aircraft (737?) have twisting main wheels, so you don't have to straighten till you touch the ground.
Yes, heavier aircraft have more inertia....light aircraft are designed so their flight controls will react in direct peroration to the airspeed they are deflected at to maintain control of all three axises.
And once again I have never ever flown any airplane that could not be landed using the crab/flare/ yaw the nose method for landing.
Speaking of twisting main wheels......
They are called X/ wind landing gear.
I clearly remember one approach and landing I did in a DC3 with X/wind gear on a narrow strip by Hudson Bay, the X/wind was really strong and I was crabbing about thirty degrees to the left to fly the center line and the X/wind gear worked so well I was able to touch down and roll out with the nose still pointed thirty degrees into wind....it was weird having to look so far to the right to see the runway to flare touch down and roll out..
What a strange question. Both ways work. Why does it matter which method is employed?
Why is my question strange?
Of course both ways work, in fact you could fly final approach inverted and roll upright just prior to the flare.....but any passenger would not feel comfortable......