Skin Favoritism kills player interest just like champ class favoritism does.
To clarify, with the upcoming True Damage skin line, it is clear that Riot pursues the quickest path to money first and foremost before they pursue player integrity. Basically, they can care less about their fanbase as a whole, they rather chase the bottom line easy picks. Back in the early part of the game, Teemo got spammed skins cause a lot of their younger and female fanbase saw the character as cute. He was easy to play in-game and as a result, Riot threw skins at him constantly. Thankfully, Riot wasn't too stingy on one champ, as they also released skins broadly for each champ as they could. I remember a time back on the skin idea boards when rioters would even clamor to make sure each champ got something cool or unique.
Now it's 2019, and Riot/ Tencent has went all-in on only pursuing the most profitable of their fanbase. They ignore the most loyal. Loyalty makes more money in the long run, as you keep all corners of your fanbase consistently content. For instance, if Ornn had gotten the skin in True Damage instead of Yasuo or Akali or Qiyana, no one would complain. Instead, Akali just got her fourth skin this year, and Qiyana immediately gets a prestige skin JUST after release. No other champ has gotten that kind of favor. These conditions lead to an upset fanbase, and eventually a drop in playing.
A lot of problems in our game throughout the years lines up with how Riot treats the design of their game, too. Because a lot of casual players like playing easier champs, adcs, supports, and mages are given a lot more love in balance than any other class in the game. In addition, because of these vocal individuals, Riot has turned League into this 15 minute slugfest that lasts after one skirmish. Back in the day, we would have said that current SR should have been its own mode (URF). All because Riot keeps chasing the bottom line.
So if you plan to have Akali, for example, to get another skin next year and continue to ignore the other corners of your fanbase, go ahead. Just don't be surprised when your players keep falling off due to neglect.