It's the law of supply and demand at play. If demand is high for goods, then the producers will take advantage by raising the prices of those goods. They will raise the prices higher and higher until it negatively affects their profits. YOU might not be willing to pay extremely high prices, but the people at the top are. Once they spend, the people who spend less than them are less valuable economically. Think about it. If you have 2,000 people paying you 25$ for a product, and 100 who are willing to pay 10$ for it, what price will you sell your products for?
YOU might decide to be nice and sell it for 10$ each, even though you are missing out on more money... but YNK/PW won't. In their eyes, your group of people is less valuable because you give them less money. Their main goal is not to make YOU happy, but to make the big spenders happy. It's all about the money. That's what it's all about. In my opinion, they are making bad choices. Not only are they sickeningly greedy in my eyes, but they are missing out on more potential profit. If they lowered their prices, they could be raking in more money.
At the moment, there are just a few big spenders. They used to have lots of small spenders, but I believe that they gave YNK more money than what they get now. Look at the old Xor Rohan. The developers had low prices, but this gave them a huge playerbase that did spend something. They say that the developers were often on vacation, drunk, partying, etc. I wouldn't say it's too much of a stretch when you do the math. Let's say you had 400 players who spend 15$, 200 who spend 30$, and 75 who spend 50$. That's $15,000 about every 2-3 months... YNK probably made more than this, but they definitely lost some after they release epics. They got a quick spike in profit at that moment, but it had to have fell in the following months due to mass quitting.
TL;DR: They are a business whose sole goal is to maximize profit. Your happiness is marginalized.If you are not a big spender, they don't see you as valuable.