I like UTG parts. I have several of them. I have UTG folding gas block sights on my AR15 and really like them. They work fine. To my knowlege, the UTG parts that I have aren't copies of anybody's products. A certain amount of copying goes on in all products. Look at all the AR15 look alikes.
I also like Magpul and thought at one time that plastic backup sights that could be purchased on the internet labelled "PTS" were actually made by Magpul or a subsidiary. They are not. I was cheated.
Magpul does have a PTS division, they don't make the parts (even though someone here once posted a link to a airsoft sight that said otherwise....except that airsoft company only sold the real full priced stuff.)
I blame Magpul and some of the other companies being ripped of in part for their own problems. The Magpul sights I bought were obvious copies. It took me about 5 seconds to find them on the internet. It would take a Magpul employee about the same amount of time to find them and another 30 seconds to send the offending retailer (in the US, if Magpul does indeed have legitimate patents and copyrights on their products) a form letter asking them to stop selling an infringing product. (I've been thru this in a company I worked for.) If the US retailers stop buying the fake parts, they will go away. The chinese importers can be stopped at the ports with an injunction.
If you have a patent, you have to be the enforcer, you have to keep your eyes open for bogus copies. The government doesn't have the resources to do the looking for you. There was a member here about a year ago who was running to Magpul, etc. everytime someone mentioned/bought knockoffs. That's nice, but it really is Magpuls job and if they don't care, why should we. I haven't seen that person active here for a long time.
There are copies of Magpul's excellent BUIS sights out there. I got suckered by a set. Whoever built the stuff I bought did a crappy job. They aren't even 5% as effective as the real stuff. The only thing they have going for them is that they kinda look like the real thing.
I understand the idea of trying to pay a bit less for accessories so you can get other things. It doesn't always work that way, though. If people want to buy them and use them, go for it. Maybe you'll get one where all the tolerances on the cheap parts happened to work well together and your sights actually are useable. Mine didn't.