Of course there useful,just like any other performance measurement.
If a car does 0-100 in 6s you have a 14 sec car
If a car does 0-100 in 5s you have a 13 sec car
If a car does 0-100 in 4s you have a 12 sec car
While this is a generalisation you get the idea,where it does get blurry is when you start to add a modified car.
Big turbos(or incorrectly sized ones),gearing,tyres, high stall convertors, nitrous can all alter the 0-400m time dramatically and the 0-100kph.
Because almost all "new" car manufactures use these figures its easy to compare vehicles.
As for 2wd guys who think 4wd is cheating.
Well all you have to do is next time you line someone up at the lights(at the drags) just wind down your window and ask if they could please take off slowly and then race when you catch up as your undertyred/overpowered car is only fast after 80kph,I'm sure they'll oblige