Damn, there's the first.
Ok, I'll not bother explaining why your camera analogy is way off, but just let's assume it is.
Next: Why would a replica manufacturer make a crappy case, retool and do it again?
Imagine if you will that there are a huge number of replica manufacturers and that one of them releases a Planet Ocean. Then, another factory sees that success and decides to take a bit of it. They decide to make it better so that the distributor, the real power player, chooses them over the older factory. This is the second gen. Now, a third factory sees how the first two factories made a killing off the Planet Ocean, but decides to make one even better so that the other two can't keep churning out the lower quality watches, forcing them to retool to compete. Then, the first two come back in the game and make 4th and 5th gen, competing for the distributor's eye.
Does that seem remotely feasible?
Arguments against would have to include a mafia-like godfather of replicas who controls all the factories and forces them to make incrementally less crappy models each time. This is so unfeasible a theory that we have to go with Occam and say it's not the case.
Cynicism is a great quality, but not when it introduces fantastical theories.