Is there any specific reason? With server version 1.7.5 and down, anyone on 1.7.2 to 1.7.5 can play on the server without updating. But past 1.7.5, nobody can play on it without updating to 1.7.6 or 1.7.7.
@Ar7ific1al can someone at least tell me how to do it. I can be wrong but I read that it fixes some bugs and other stuff. It doesn't take ages to update. I got a profile which uses the latest version. So now I needed to make a new profile to play (which is not really a big deal either).
Left side of McMyAdmin, it tells you a new MC server version is available. You can stop the server and click that. Or you can click Install next to Server type under the Server Settings tab in the configuration. You're right, it shouldn't take too long. Easy to update, no dependencies like we have on NanoBlock, PokeBlock and CraftBlock with mods and plugins.