I should have been more clear.Its a lot more work to build a modified version of a proven, existing design, than to build per plans, but much less work than starting from scratch to develop a “totally hew design”.
Almost every airplane in existence has adopted features of previous designs.
It is ok to borrow ideas from an existing design, but you have to admit that quite often that someone sees a "StarBuster XYZ" and starts proposing changes to it. Then after a few iterations, it should no longer be called "StarBuster XYZ", IMHO. I have even seen a notation on some plans to the effect: "If you make any changes, do not call it a "StartBuster XYZ" and I [the designer, not me] absolve myself from all responsibility."