You could give Oasis a feedback worth 1 billion dollar and they still won't listen to you. But yeah, the price in both ino event and time limited shop is over expansive with stamina potions but since they are giving p2w stuff in these event, particularly ino event, they don't exactly want f2p to get their hands on that. I think stamina potion is more like a rebate if you intend to recharge on these events.