I never really figure out the reasoning behind the adapters for the speakers, most people just toss out their old speakers anyway. The stereo on the other hand the adapters make sense. Most people add in an aftermarket stereo and keep the stock deck in their garage/attic/closet then when they want to sell the car they put the stock head unit back in. Nothing is more annoying than trying to figure out what wires are for what when someone hacks up the stock harness.