We added 2 new flavours of Bitcoin within a year and this is just the beginning of this new trend to fork the original Bitcoin into some Alt coin. The thing is, this is profitable for early adopters and also a strategy to boost a Alt coin, because it is linked to Bitcoin by name.
Nobody is saying NO to the free coins, so this is not going to stop. There will only be 21 000 000 BTC, but there will be Billions of copy cat Alt coins coming our way.
I definitely see the trend continuing as well. Bitcoin is by far the biggest network, so it's naturally a way to bootstrap use of a new altcoin. But what effect will this have on the markets? Will the forks draw investment money away from Bitcoin (newcomers put money into forks rather than BTC)? Will the forks draw investment money away from altcoins (because people need BTC to get the airdrops)? Both, or something else?
Fundamentally, these forks are good for long term BTC holders, because if they are worth anything at all, BTC holders can liquidate them to accumulate more BTC. In the shorter term, I wonder if they could damage the price of BTC, though. That doesn't mean the price has to go down, either --- just that money is being invested elsewhere instead of BTC.