I think you may be misunderstanding the nature of magic item rewards in a system like 4e, in which items of a certain "plus" are treated as default elements in PC build.
It is not a "treadmill" in which the players pointlessly run to stay in place while being tricked (by what means?) into thinking they are really earning rewards.
The pleasure that players receive in watching their numbers go up in 4e is certainly not a pleasure in greater real-world power. Which would, I think, be absurd.
Nor is it a pleasure in a greater likelihood of succeeding at the challenges the game throws up, because a GM who follows the published guidelines will respond to bigger PC numbers by boosting the numbers of the NPCs and monsters. In 4e, to the extent that players increase their likelihoods of succeeding at these challenges, it is because they improve their play, not because their numbers get bigger.
The pleasure in numbers getting bigger derives from the the ingame implications, namely, that the PC will now be confronting challenges carrying more ingame signficance, and thereby having the potential to carry more real-world story weight. To put it at its crudest, every +1 to hit or damage takes the PC that much closer to being able to confront Demogorgon and win. That is not a treadmill, and not an illusion - it is a genuine feature of the game. Changes in the numbers mean a change in the story - just as the PHB and DMG explain, the fictional scope and fictional stakes grow together with the PCs' numbers.