on the other hand _expanding_ the product is a different story. As time has changed, people are more and more behind the idea of disliking "dead" levels, the rules behind pathfinder _do_ work differently than they do in 3.x, and enough time has passed that a company might have found that while idea a seemed to work fine over time it actually brought up a different problem and now they've got a better solution.
Plus, while gamers _can_ do conversions themselves, they're more willing to buy a product that's already done it for them and that they don't have to worry about whether or not it's been done "right". In theory at least, if someone's selling a product then they've already covered whether or not the rules are "right".
