It was about whether this was a just war, and essentially whether any good effects achieved (getting rid of Saddam) could outweigh the bad effects (some of which we are seeing today).

Arguments about "the morality of the task" are arguments about precisely that kind of thing.

I wrote "But it didn't need hindsight to know this was going to be an unholy mess, because outside millions of ordinary people were shouting themselves hoarse predicting it."

Are you really saying that we weren't predicting that it would all end up in an unholy mess?

(I just can't read the analogy implied in your last sentence - but maybe better not unleash an Irish argument in this thread.)