You're kidding, right?
It has everything to do with money.
I don't think you know how a business works. If you charge enough cash, you can afford to spend more during production to ensure a better-looking, more durable figure. Ask yourself: you're not going to put out solid gold for two lousy cents, are you? Didn't think so. You'd be bending yourself over just to please whiny customers and forum-members who expect way too much from a company that primarily markets $15 toys. And that's not profitable.
Bottom line: the only way NECA can put out higher-quality products is if they invest more money in making them, which can only be done if they increase the price at which the final figures are sold -- and they can't do that past $100 because they would alienate their target market. Even if there are high-end collectors willing to shell out $200 for a perfectly-painted NECA Predator, going through the process of finding and employing a newer and better factory would cost extra time and money in itself. In other words, it's a big pain in the ass and the company is doing fine as it is, so they're not going to bother. Only if they were close to hitting financial rock-bottom would they consider giving their business model a complete makeover (which is what you're suggesting whether you realize it or not).
This explains a lot.