Brake rotors are drilled to reduce weight in racing applications, where more braking isn't an issue (just use larger rotors and pads). Might also be some minor effect on cooling, too, but not much. Lifetime isn't an issue, they are usually shot by the end of the race and won't be reused anyway -- safety hazard!. Ditto for pads.
They have very little effect other than looks in normal street use. I have my suspicions about wheels with thin enough spokes to show the rotors anyway, but the holes are only there for looks, nothing else.
Be trendy or die!!!!! That's why I drive the last W108 chassis in Evansville.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!