I don't mind grenades (though I can see how they get annoying on a little map like Junk Flea.) In fact, for the most part, I think grenades add to the game. It is fun to have a weapon that requires a totally different technique and has different capabilities than a gun, one you can throw over obstacles if you hear a foe wading through water or opening a door, for example. The grenades make it wise to use the real life tactic of "not bunching up." And the frag grenades, because they do so much damage, give a beginner a real chance to kill an expert, which makes the game less frustrating for the noob and more dangerous for the pro. And because you only get two grenades per life, there is a limit to the amount of spamming that can go on.
While I like grenades, the mines annoy me. They slow down the game, for one thing. And how the hell can I tell if a mine is friendly or hostile? I mostly play Elim, and I just shoot or grenade any mines I see.
The best thing about explosives in CA is that you can start a no explosives room, so that the players can choose whether to deal with them or not.