It appears that IOI spent a lot of time upgrading the guided tutorial missions, and putting a lot of effort in setting up the guided mission stories. Hitman III was also created with more accessible easy kill opportunities.
IOI knows that the majority of buyers of their game will be the casual player, who don’t play much more than the scripted and easy stuff, before falling off of Hitman.
While those that play a lot of Hitman would like more investment in feature contracts and other specialized content, it is not effort that would have much payoff, since most who buy Hitman would never play it. The core Hitman fans are vocal but they are a small minority of those that buy the product.