My 53' gooseneck dove tail is tits for hauling cars & minivans that have the longer overhang in the front. You would never get them loaded on a straight deck (without scratching, tearing up the front facias & airdams) without some seriously long, heavy ramps. It has an angled neck that has flip down ramps that allow you to drive one all the way up on the neck.
My first trailer was a straight deck and I was always looking for a high spot to unload onto to get the ramp angle decent for cars & minivans.
Like others have said they are also really nice for hauling the wheelers I just drive them off & on without the ramps.
I had 2 samis and a tracker on the bottom deck once with the neck ramps down it would haul 4 easy possibly 5. It also has some extensions for the front that I took off cause they get too close to the cab on the tow rig it would haul 5 easy with them on.
One time my kid & I went & picked up 3 FSJ along with some spare engines, trannies, body prts, etc. & came home 500 miles with it all on this trailer I wish I would have got a picture of it. It would have looked good in the big stupid loads thread!