I agree with
@PsyBorg.
I would add the importance of RC planes to teaching kids the importance of science, technology, engineering and mathematics. There are so many STEM applications in the RC world, it’s hard to over sell. I can’t tell you how many kids I have encountered, that had absolutely no interest in STEM. I put a plane in their hand and start to explain the math and engineering to them. I never grow tired watching the light go on inside their head. STEM can be useful and fun.
With store bought planes, the STEM has already been done for you. With a scratch build plane, you mush do all the STEM work.