Refunds are essentially a "What-if" fear for many people. For me, I find myself being too fearful to refund anything I purchase because of the fear that I will eventually need at least one in case I purchase something that I simply don't enjoy. I also am fearful to use a refund on stupid purchases (Soraka at full price 260 RP being my worst purchase ever) because I know how easy it is to just make a purchase without really thinking about what I am actually doing (check my Mystery Gifting and Mystery Skin purchases, and you might see that I'm very good at doing that! :D)
I saw one very good idea in this thread that says that if the content has yet to be used, it should be refundable without the use of a refund token. This is a great idea, and I would like to expand on that a bit further. I think it would be acceptable to allow players to purchase content and then test their content in a custom match, just to see what the character looks like on their own screen, from their own perspective. Then, after seeing the content in all of its glory, the player can make the decision to either keep it or give it up. Restrictions would need to be in place, of course, to ensure that the skins aren't just used in custom games with other players, but I think it could be beneficial to players, as they don't waste their money on a product they have second thoughts about. You can also make it so that skins are on a free-to-play rotation similar to champions, where any non-legacy skin can be played for a week to see if people like the feel of it before purchasing all together.
For me, I think I have a few ways to actually help make refunds be a valuable asset as well as something that isn't a fearful decision.
1.) Make it possible to purchase refunds using a massive amount of IP (15000, similar to Summoner Name Changes)
2.) Reward refunds based on challenges in-game (an idea that I have seen be implemented in World of Tanks with their challenge system).
3.) Give a refund back to the players every 6-12 months, so that if you use a refund, you can be sure that later on that you won't be in a bad situation.
4.) Reward people based on good behavior. This would give a bit more significance to earning the honor titles, as those have sort of died off.
TL;DR - Refunds are way too daunting to use without regret over doing so. This can be solved in multiple ways, such as skin testing, rewarding players with extra refunds via challenges or behavior, being allowed to purchase them via IP, or simply giving players another refund every now and then.
I know it was a long response, but I thank you for reading through it. I hope this helps.