It really depends on the mod. Some out there have plenty of models floating around that may just be sitting there unsold because of clones. But I think the reason that clones are so popular right now has to do with the accessibility of some of the more "popular" high-end mods out there right now. Everybody wants one, but only a minority are lucky/privileged enough to actually own one. There are two factors involved. One is price and the other is the ratio of supply to demand. If I only had a nickel for every time I learned of a mod I would do anything to get my hands on only to find there were no more being produced, I would own two of each one! I'm sorry, but if you don't want to/can't manage to make enough of/make available enough a product that I really want for me to get it at a reasonable (or even unreasonable) price, then I'm forced to either buy a clone or go without.
From a business perspective, you'd have to be excruciatingly imperceptive not to understand the profit margin there, given the general simplicity and reproducibility of the designs versus what people would be willing to pay for the manageable quality and performance expected from said product. Of course, even the bottom dogs can benefit from these conditions. But it's not because they're evil monsters. It's as much a product of the desire for profits as it is a product of limited supply from the people creating the initial market with the introduction of these products. They spawned markets they couldn't fully please and clones are the result. That demand is still out there, you know? You can't blame others for stepping up to fill those gaps. That's money the producers of the originals could be making too if they were pursuing it.
You wanna know the solution to clones? Out-compete them with your originals. If it's popular enough to have numerous clones, then it's popular enough to blow them out of the water, economically. There should be more than one way for these inventors to capitalize on their ideas without losing portions of their markets to clones. If the product is really good enough to be cloned rampantly, then there is a feasible, profitable business model that can better take charge of the market portion being ravaged by clones to be schemed up. Barring that, you have chosen your niche as a premium, boutique vendor with an inherently small, but loyal market by your own business model. You can blame whoever you want, but given the nature of both business and humans, the outcome is quite predictable there.