Idealism is awesome, it makes for great songs. And without it, the entertainment value of history would plummet.
...but it is horribly impractical taken beyond a very minor level.
Or
very lucrative, to the right people.
Regarding war, contrary to popular belief, the world has never been more peaceful than it is today when viewed in regards to the size of the human population. Statistically speaking, the chance of any given human dying at the hands of other humans is utterly microscopic compared to what it used to be, once upon a time.
And it's an ongoing trend. Even counting both world wars and all the smaller ones, the 20th century was more peaceful than any century before it in recorded history, when measured against population size. I believe the biggest reason why we perceive our own times as being so violent is because we now get every war spoon-fed to us through the media - unless it happens in Africa, that is.
And media will keep feeding us news about people killing each other, and we will keep paying them to do so. Because, despite every moralist wagging their finger to the tune of the contrary, people killing people is, has always been and will always continue to be great entertainment.