$20 for an ingame skin? I'm fine with that. It doesn't affect gameplay.
TLDR: you should probably skip the rest past this point, lol
Hell, I bought a Caterpillar for $300 and I could have earned one in game and saved the money.
Having expensive skins doesn't hurt gameplay and it's the gameplay that makes a great game, not skins.
So completionists have to have absolutely everything. That does make things more challenging for them since it requires a fat wallet. For some, completion is unachievable because some things are locked behind pay walls or limited time only walls.
I think that as a completionist, you should set your own goals since some things will always be out of reach. Competative people can't all be #1 in the world, so they lower their standards to be in the top 10% or even 5%. I think that it's fair that completionists do this as well. You can get everything earnable in game, or everything at the time, or everything except your small list of unobtainable items.
Skins have been a part of games for a long time, including paid skins. Certain skins are not avalible anymore. Like if I wanted an F7A mod kit for my Super Hornet, I can't get one anymore. I cannot complete a skin collection for Star Citizen unless I find someone willing to sell it for probably a couple hundred dollars. Still, this doesn't ruin my experience with Star Citizen or make it a bad game. The gameplay is unchanged, only the experience is slightly different. I don't have a golden ticket either but that's ok too.
If people want to give EA $20 for a skin, then let EA sell $20 skins. It's not an underhanded business practice to sell skins.
Some people complain about not having a complete game when they get it because they don't have the skins. That's like me buying a truck and saying it's not complete unless I get leather seats thrown in for the same price. A truck with default fabric seats is still a complete truck even without the leather seats.
Most games sold are complete (exceptions like No Man's Sky and stuff left out for simplicity). If the game functions and has content, then you could argue that it's complete.
Some games have lots of content held back on purpose so that it can be held randsom for extra money. If this is upsetting to you, then you should really be looking at if the game is even worth playing. In this capitalistic setup, companies can charge whatever they want for their product. If you don't like it you can either not support them or demand that laws be placed to keep this from happening.
As long as paywalls are not placed to stop gameplay or progress, I'm fine with $20 skins. Hell, sell me a $50 skin that I think is totally amazing, but don't make it a pay to win skin with extra bonuses that others cannot get without paying. Pay to win is not ok.
People can set their own goals. If you want all the skins, then you need to understand what thst means. Money, dedication to sales or times events, and more. Just like people who strive to be number 1 in ranking understand that they need the best skills, experience, and gear to be number 1.
Companies need money, so they charge for various things. It's ok to charge for a different experience, like skins, but not ok to charge for gameplay, like better gear. That's just where we are at right now and if you don't support this idea, then don't support the games that are built on this idea. The loudest voice you have with companies is your wallet, so if $20 skins upsets you, then don't buy the game.
I used to love the battlefield series. I loved 2, 2142, 3, and 4. I didn't buy Hardline, 1, or 5 because I did not agree with EA holding half the game behind season passes or constantly making more games that I would have to buy again and climb the ranks all over again. I don't support that idea, so I stopped supporting them.
I don't agree with OP, though I respect that he's drawn a line where he thinks it is no longer ok for game companies to do. It takes a bit of effort to do this but more effort to change things.