I'm not sure there is any evidence to say copycats helps promote the original. Our major examples are Bitcoin with it's swarms of alt coins that have done nothing but dilute the market. Ie the worst thing that could of happened to Bitcoin is a load of copycats that make a mockery of digital currency.
The other major example is of course NXT which is being destroyed I believe by inferior clones.
How about posting any evidences of opposite? I myself and at least two more people I know got into cryptocurrencies starting with Litecoin, Zetacoin, Quarkcoin and of course Nxt. Bitcoin looked too expensive ans stable to buy it. Copycats look like a perfect way to double or triple your investments if you're just starting and don't have much money.
You're clearly talking about two separate things. You are talking about profitable mining and generally making some short term profit while I'm talking about the long term viability of digital currencies. All the coins you mentioned have not had a steady increase in value but resemble more a pump and dump with no one taking them seriously as a real currency apart from NXT which is not the same argument cause it as a new code ie not a clone.
Of course no one can give 'evidence' but we do know your side of the argument of releasing code and seeing a ridiculous amount of clones that I believe do nothing to further the uptake of digital currencies and their viability as a real exchange of wealth (99% of coins are only useful once traded on an exchange for Bitcoin or fiat to have any serious option to buy something). So I think you are on a sticky wicket if you think the ever growing flood of shitcoins and IPO's 'helps' Digital currencies rather than spread the wealth among more coins.
And we cant know what would of been if source codes weren't so easily cloned. But imagining a situation where we only had Bitcoin, NXT, Qora, EXO etc would be make for a far more stable respectable situation. I mean you would get genuine interest and focus on new innovative coins due to their rarity and people wouldn't be bouncing between so many coins but would probably have a foot in the major ones. Plus if the only way to have a new coin was to actually create one then it would naturally lead to innovation and people striving to 'make' a new coin and not a scam clone.
So yeah we cant have 'evidence' but I know with a bit of an educated guess which one I personally would prefer, beyond my preference you will have to ask others.