I am not sure that this is the appropriate place to post my comment, but you are correct in your observations with Pure Fishing, and other large companies in the tackle industry.
Simply put, it is much cheaper to copy product, than to develop it AND test it properly. It has nothing to do with "right and wrong", "ethics" or even patents or laws. The big companies have the big legal budgets,and they will win, every time.

One example I will share is of my Rods. My logs are registered here in Japan, which takes a great deal of money(for a small company like mine). My swimbait series of rods were made before ANY company in the USA or Japan had released their first swimbait rod.
I filed to register "BBS" or "Big Bait Series" for my rods already in production. My BBS label had been featured in hundreds of pages of print, and on National TV.
Daiwa notified me that I could no longer use my labels, as they were going to register (after me) BBS for their reels and rods.
Even though I had filed first by a year, Daiwa's registry was approved.
My lawyer I keep on retainer against their whole team of lawyers and unlimited legal budget--the outcome is a given.

One thing that is odd, it that I have produced and sold several million dollars worth of rods with the BBS label, and have never been sued for using 'their' registered label. Even though they would win in court, my product had been in the media years before theirs, and that might make for bad publicity. I think I got lucky.

So why do large companies copy Basstrix (Hi Bruce!) Roboworm and the like. Because they can.

Finally, let me say that I have no "beef" with Daiwa or Pure Fishing (The latter I have done some behind the scenes business with).

As I said in my Tripple Trout post, "Who looses in this copy game?"
As Rob stated, "The Fisherman, or end user" by not getting product that is never released, or developed, even though the big players have the R&D monies to do so.

Just my $0.02.

"Known as the person who introduced swimbait fishing to Japan"