D&D next is clearly designed to make old(er) school players Wotc customers again. Including Caves of Chaos is an obvious marketing move towards those players, regardless of the quality of the module.
As can be seen from this thread, Caves of Chaos has a hallowed status among old school gamers. Moreover, many gamers playtesting now, already have played B2 at some point in the past, so they have some experience to build up a good game from the skeleton provided, regardless of the quality of the actual module. Finally, gamers may connect their experience playing D&D next to old memories of playing B2 before. This will make the play experience more "magical" regardless of the quality of the rules system. And D&D next needs positive buzz from the first play-test release.
As can be seen from this thread, Caves of Chaos has a hallowed status among old school gamers. Moreover, many gamers playtesting now, already have played B2 at some point in the past, so they have some experience to build up a good game from the skeleton provided, regardless of the quality of the actual module. Finally, gamers may connect their experience playing D&D next to old memories of playing B2 before. This will make the play experience more "magical" regardless of the quality of the rules system. And D&D next needs positive buzz from the first play-test release.