If one of these altcoins has such a brilliant idea then what would stop it from being implemented into bitcoin? We have the testnet that allows people to test new features or anything they want so there is no real reason to have to use an altcoin to develop these new ideas. IMP people throw money at altcoins because they want to speculate on the price.
A person can force his idea to be implemented into bitcoin, if his idea initially doesn't find acceptance amongst developers. However, if he releases an altcoin, proves that people like his idea/feature, then it is more likely that these features would be integrated into bitcoin.