Game developers manipulate player desires by presenting the same options differently. Player reactions are empiricably testable with cash shop setups.
I frequently cite the example of having a “hunger” debuff versus a “well-fed” buff. These can be designed to be numerically identical, where the character has higher base stats that are debuffed by hunger or lower base stats that are buffed by food. You balance content around the higher number in either case. Players will complain about a hunger debuff but feel like they have been given something extra with a food buff. Even if the numbers are identical, humans are unhappy if you tell them you are taking something away from them, whereas they barely notice if they fail to gain something.
Many cash shops have some sort of lottery option. You can give the developers $X for a chance at items or whatever. What you see at least as often these days, because we would predict that it works better, is giving you a lottery ticket or prize you can pay $X to unlock. In the former case, you can play the lottery by giving me $X; in the latter, this lottery ticket is now yours, but you cannot redeem it unless you give me $X. Same lottery, same prize, same $X. If you doubt which implementation yields more sales, look at where the developers are betting. Team Fortress 2? Locked crates with keys in the cash shop. Guild Wars 2? Black Lion chests with keys in the cash shop.
Developers can make this more concrete by adding time pressure: the box/ticket expires in a week or after the event. Some players might still see a locked chest or lottery ticket as a failure to gain, but if it is going to disappear in a few days, they have definitely lost something, even if only an opportunity. The perception of scarcity also plays in here; you always have access to thousands of TF2 crates and GW2 chests for a few cents, so it is harder to instill the idea that you are losing any opportunities, while other games might make those drops less common (but still give the player frequent opportunities to buy things). Hence TF2’s time-limited crates, and doesn’t GW2 have occasional seasonal Black Lion chest items?
: Zubon
I think player direction also plays a role here.
Using the food example; if your game is focused around survival as a major theme, hunger hurting you is seen as a challenge to overcome, and so food is easier to make the focus for your game. If that same survival game had food as more of a buff, some players (due to math tax) wouldn’t see that as a big focus or major need, and your game (to some) wouldn’t be as dire or ‘themed’.
Hunger is a tricky example of the rewards-not-penalties idea because it’s one of many things that is conventionally taken care of offstage (in fiction as well as in games). So by making characters suffer from hunger, not only are you introducing a penalty, you are converting the default of implicit feeding-yourself behavior into explicit feeding-yourself behavior, which creates immersion issues. In games where feeding yourself fits as part of the game challenge — nethack, for example — it seems to me that players are satisfied with hunger being a penalty. MMORPGs don’t seem to fit a constant requirement to feed yourself into the game challenge in a fun way, so truly requiring it all the time would just be annoying, so they wimp out on hunger being an immersive penalty, instead continuing to have characters feed themselves offstage (as opposed to game mechanics of getting desperately hungry, starving, and eventually dying unless an explicit feeding action is performed by the human subscriber).
Having characters occasionally benefit from a special meal dodges this problem by leaving routine meals offstage. Having characters get hungry moves routine meals onstage and then faces the dilemma of (1) being unfun by enforcing a routine requirement with (ultimately) death in a game where that’s no fun or (2) breaking immersion by not following through on the routine requirement to eat or die. It’s similar to bringing outhouses on stage and introducing a “need to pee” debuff: it’d be tedious to have characters die of ruptured plumbing and it’d be silly to allow characters to ignore “need to pee” for months with no more than a minor constant debuff.
Note also that WoW’s hunger for pets did somewhat successfully bring routine feeding onstage in a way that added to the game for a significant fraction of their customers. (And they didn’t wimp out on it being an immersive penalty: like lots of other things in the game it was cartoony rather than serious simulation, but the problems from hunger would pile up until eventually the unfed pet would leave.) They threw it offstage later (along with various other maintenance requirements like ammo and soul shards), and they were probably correct that a lot of their customers didn’t like it, but I read enough complaints at the time (and felt enough nostalgia myself, though I had only played a hunter up to midlevels out of curiosity) that it seems clear that a significant fraction of their customers did like it.