do you not think there has to be some protection for people who create and develop?
suppose you invent the scissors after a lot of development consisting of time and expense and
show it to me as a potential investor . . .
"Thanks lads, that was a great idea, there's the door, I'll produce this myself,
come back to me with your next invention and I'll just rip you off and copy it, again...simple!" 
Honestly, it depends on what your priority is.
If your goal is to produce a small minded society of petty people who look at 'innovation' as a financial issue then intellectual property is a useful concept.
If you want society to really develop though it is probably better not to use laws to monetize and restrict ideas.
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As for your scissors idea, most people who have 'invented' stuff are adult enough to realize that they were only building on ideas that had preceded. If somebody came to me and said he wanted credit for inventing the scissors, or whatever, and wanted protection from other people possibly using that idea for popular benefit, I would kick him in the nuts and tell him to invent stronger pants.