The reason that there are too many altcoins is that, every altcoins serves a different purpose than others. Some altcoins can be used to buy products and services, some are use for transactions, some altcoins are for betting and gaming. To answer your question yes they have something unique about them. Also one reason that there are so many altcoins is because of competition, every altcoin wants to surpass other altcoins so developers keep on creating altcoins better than other altcoins in terms of service, security and high prices.