How about currency manipulation, where a new currency can be introduced further down the line. You must have skimmed past that section, or felt that this perfectly fine to use psychology against people.
it can be used as manipulation, but it is even a necesity for determined meccanics, for example, they can't actualy give you money in the game, but they can give theyr fake currency in order to alow you to "access" the non-free contenent even with ingame meccanics .
the problem there is looking at evrything as an exploit .
as i said, most MTX require regulations ( about targeted deals , gamble , abuse of personal information)
but the MTX itself as a way to make money for F2P its totaly accettable from my point of wiev ( for example LoL use MTX , and have varius currency ingame (that is not always simple to see the value of it) , but i find that version of MTX actualy kinda accettable, the only thing i would like its a simpler way to understand the value of theyr currency.)
A store is very clear upfront what it is your purchasing, and there are consumer rights in place of you are mis-sold something. A store can't manipulate currency on its own to skew sales in its favour because you've shown an interest, there's a financial regulator that keeps money in check. Also most stores don't take away something you've purchased within a short time of purchase.
and there is the fall ... a store is not very clear , there are regulations but they still alow a form of unclearness . they make "all out to 80% of discount" evry year , you can see the instore discount ( and it has to be the real one , or its illegal) but you can't know the actual value of the merc, you are "pushed in" by the advertise , and by showing all other costly alternative and " pushing" you to buy with the "LIMITED TIME OFFER" .
no, psicologicaly , there is no difference from MTX to a shop . the value of money itself is something that is in costant change , so the presence of "special" value is in some case a trick to make you use the currency itself, but you still need to buy it and looking at how much money you are spending .
i guess we disagree on the gravity of a simple ( no abuse of personal information) and non-gambling MTX form .