In my experience, players are less likely to invest into time-limited cosmetics… And time limited items as such, for the most part. The reason? A noticeable part of F2P playerbase is comprised of people who do not commit to the game on a regular basis. This is especially true for old Ragnarok Online fans, who (considering how much time has passed since they played RO) are for the most part, employed and perhaps, even married with children by now. Which, unfortunately often means that they can no longer play every day - and are much less motivated to buy items that are bound to expire in a week’s time.
If there are cosmetics in the cash shop they should act as unlockables, but not as pay-to-rent stuff. I don’t mind paying for a weapon skin/costume/shop-exclusive dye set. Or a fancy-looking mount/pet. Or some gimmick to facilitate faster/easier travel (teleportation?). Or for exp boosters, for that matter - I’d rather welcome those so that I have means to catch up to people who play more often. But paying for something I may or may not be able to use in a week’s/month’s time is rather meh.
And please, PLEASE no “Pay2Win” grade stuff. If given a choice between p2w and subscription fee I’d go for latter any day,