Long Challenges give me time to put to actual code a lot of complicated data structures techniques that I have heard about/discover during contest week. The points serve as a motivation for me to write the code. I think I implemented Min Cost Max Flows, HLD, Gaussian Elimination, FFT for sums of powers etc…, for the first time here only because I was getting points in the long challenge and it is good motivation to learn stuff and add some more skills to my repertoire.
By the way for the tough questions I doubt if there is much plagiarism, as coming up with solutions isn’t trivial. The smart ppl who come up with it don’t like to reveal the idea, coz they worked to solve it. So basically stop crying about ratings and what ppl are doing and work your way up like you should if you really are so affected by ratings.
Long Challenges provide an opportunity to learn which is why you see top coders participating there. It is the hunger to learn more than anything else [For some it’s getting some cash, but those are at a different level]. Short Contests don’t teach you as much.