Where's the problem?
It's purely cosmetic, on top of what is already in the game and not overpriced.
I've never bought any cosemtic stuff ever, but there are many that do.
It's also the only way for companies to make a decent amount of money nowadays as video games are far too cheap. They are still $60 when they should be closer to $75.
So you should rather thank anyone who is buying stuff like this, as this keeps the costs down for all of us.
But that's false informations from those same companies.
Companies make less games => Spend less money on games => And make a ton more profit. EA is just one of the examples but most companies try to do the same.
2017 was more expensive for EA because of SWBFII 'free' dlc where they lovely used the 'you can earn anything but it needs 100 hours for a costume or buy some lootboxes fiasco'
I don't know who it was but it was EA or activision who were trying to come up with a new idea: People who buy more DLC/extra's/costumes will be lined up online against weaker players, while people who buy nothing will play against stronger players and hopefully feel the need to buy something.
Is the "development cost" graph an average by game?
Otherwise, do you realize that it proves the exact opposite of what you're saying?
If the wiki is accurate, EA developed or published (EA sports excluded, same every year) 8 games and one extension in 2009. Same thing in 2010. In 2017, they published 4 games. For almost the same development costs. It just proves that one game costs more to make, and that they need more sales or another way to make money.
By the way, I just noticed that the French wiki I used is incomplete. I won't compare perfectly, but in a complete list (EA sports included) you have 13 results for 2017 and 72 results for 2009. If you compare this to your graph, the answer is obvious.