Any semi-competent player can easily avoid a creaer and stip it from blowing up..by killing it or outruning it.
Unless they sneak up on you, as happened to me multiple times.
Nerfing creepers is probably one of the most common plugins I see on bukkit servers. I know one person who swears by creeperheal. Explosions will destroy blocks, but the plugin will rebuild what is destroyed X amount of time later as set by the plugin config.
My server, I nerf explosions, but only on the creative world. Survival, it's basically a recreation of single player survival, just with multiple people. If someone is going to play with TNT, lava, flint and steel, or try to play tag with a creeper, go for it, just be prepared to accept any consequences.