Guys, look at the list. Those are all (relatively) close range weapons compared to bombs or rockets. Most bombs and other explosive devices tend to have a pretty high rate of collateral damage as well. Bigger the bomb, bigger the problem.
In that sense, the A-bomb (or any other similar device) is really not that great. Gas attack would at least not destroy the infrastructure/physical value of the area in question.
Use of any weapon is an act of desperation, not limited to any particular type.
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin