I technically haven't abandoned my coins, They don't really need my watch-over as they are stable and functioning fine, even reading through Firecoin, most people don't even care, its the coin they are after and it works brilliantly. If there is something wrong with one of them, let me know, I bet you I could fix it in 10 minutes or less. (Seriously.)
The value of a coin on the exchange (aka the value of the investment people have made in the coin) is highly linked to the perception of support for a coin. Nobody wants to be a bagholder on a coin that doesn't get updates, feature improvements, or even a response from the developer, so massive dumping happens and the coin eventually gets delisted on exchanges because of perceived abandonment.
Allcoin.com freezes wallets that don't have a working block explorer - I have created TECH and FIRE explorer but the OP needs to stay up to date otherwise trade gets stopped (TECH) and things just die. You need to keep your still working coins updated and actually support them!