Talk about necromancy!
Basically, a kamikaze move as it's described here generally results in a third player winning the game. I guess that's okay if you want the higher ranked player winning so you don't lose as many points (not a fan of this, by the way), but if the situation's truly hopeless and you attack one player like crazy anyway, it doesn't do you any good.
Now, there's a difference between a kamikaze attack and making a last-ditch shot at winning/ running the table. With the former, the chance of success is effectively zero. With the latter, usually the player's estimated their chances and have at least a believable shot at winning the game (though what is considered believable varies from player to player).
I don't know where you'd draw the line - trying anything at 0% chance of success (for example, you have 8 troops left, and you have to conquer 10 terts to win) is just poor form. Personally, I wouldn't attempt something like this with less than a 20% chance of success, but if it it's reasonable, I'd take the shot.
Say it's an Escalating game, and if I can kill an opponent I either get points (Terminator) or enough cards to cash again and replace the troops I lost, I might go for it. Say I had a stack of 10, and I had to kill 20 troops on one tert - unlikely, but it's still possible. It depends on the situation in the game, whether it's make the kill or be eliminated. If I don't try, I lose, and if I try and fail, I still lose, but if by some stretch of great luck, I make the kill and either stay alive, get some points, or eventually win, I'd pull the trigger there.
Now, if you're attacking every turn just to attack, and in doing so giving the game away to a third player, I don't see the benefit for you personally (unless, again, you'd rather lose less points to a colonel than to a private first class).