People see success and failure in terms of price. When price tanks a coin is declared dead. When price is good, the coin is a success.
The altcoin field is populated with attention-deficit-disorder people who are like bumblebees moving from one flower to the other. If price is stagnant or falling for a couple of months, a coin is declared dead and they move along. Altcoins do not have the luxury of going with a bitcoin type of curve due to the perception of "being dead" that will actually "kill" them as people abandon these coins. If an altcoin waits 3-4 years to do its distribution before it makes its success it will have been overtaken by so many other coins who are now offering much more than it does.
It's a weird game, but the rules are different for alts than btc. They have to make an impression and make it stick - fast.
You're forgetting something Alex, the ring signature technology is too useful to be abandoned. Perhaps if something better comes out sure, I'll see your point.
Unless a technology comes out to defeat ring signature, at least one of the CryptoNote based coins will gain in popularity over time, even if it isn't Monero.
Also, in its current specification, Zerocoin/cash still has a trusted accumulator, and thus cannot be a suitable replacement for ring signature technologies.