But I think this will inadvertantly lead to an overall increase in prices, probably not intended by the people pursuing this.
Why? Because most of these in-game currencies are sold in packs of varying sizes and the larger packs are usually cheaper per-currency than smaller packs. A volume discount.
Selling the currency like this means the euro value of a single unit of currency is variable, which obviously cannot be reconciled with a requirement to peg a specific euro price onto the actual goods thereof.
So assuming this action is successful, we'll probably see an end to the volume discount with large packs becoming sold at the same euro-per-currency pricing as small packs, and a currency-to-euro conversion printed on the actual goods next to the price in currency.