Copying IP and designs from others is an unethical practice. As such, the people conducting this practice are not going to be trustworthy for creating a reliable quality product.

Then, the customers who buy this stuff: Instead of paying a share of the R&D costs and the costs of quality, customers who cheap out on this kind of cargo cult product are instead saving a few bucks short term, only to pay the price later when the unit fails to perform long term.