Yeah these are the two most prevalent arguments against my suggestion that i've read elsewhere. The problem with the first one is that the system that riot has in place is frankly garbage, I didnt even play aram the last time your shop was around and i almost solely played kayle or ori and yet i got no skin for either of them yet i got a ryze skin like practically every your shop ive ever had. Now that i play a lot of aram I'm sure my yourshop will be useless.
Secondly it's really not rigging the system. The whole point of yourshop is to get people to buy skins by discounting them. People can only use 1 skin each match anyways and the vast majority of players use only one skin for each champion for long periods of time. Which means the generally inferior skins will simply not be purchased at all on most newer players aside from if they could get it for a huge discount. Digressions aside, All but the few champs with only one skin require purchasing multiple other skins to effect any discount on whatever skin may be left unowned not to mention that people are most likely to purchase whatever skin theyd usually use as the sole skin for that champion anyways so the vast majority of extra skins purchased for a champion for which a player already has a skin can be attributed directly to the perceived better value from the discount. Aka in many cases the discounted skin likely wouldnt even be purchased if not for the discount.
Using lux as an example, youd have to spend more than the cost of elementalist lux just to have a 75% chance of getting one of her three best skins if elementalist lux could even be one of the options available. The only reason anyone would have to do that would be to attempt to get lunar empress outside of the event time although the vast majority of people would simply save themselves like 1k rp and buy ele lux since shes vastly better anyways. The only place where riot might lose some money is on the tiny minority of people who simply buy skins just to have every skin, they would be willing to spend money on all of the cheaper skins to get a potential discount on a more expensive skin but even for the majority of champions thats still quite a gamble due to the cost of all of the cheaper skins and the chance of getting a small discount %, not to mention that the large increase from the majority of players now buying skins due to having champions theyd actually like a new skin for would easily offset any people who are "manipulating" the system