That is the only option, because in other cases some nodes will receive payments and others do not. And that's not how it works: you have a route from A to B and this route as a whole is either completed or not. If it is completed, then fine, every node updates its closing transaction. But if there is any problem at any point of this transaction chain, then everything is rolled back to the state as if that payment from A to B was never started. If some node will try to use any state of "half-baked coins", then some penalty transaction will be broadcasted by some other node.