It is another example of the new form war takes when it comes to casualties: highly asymmetric. It has recently been in the news, thus on my mind. No other reason I bring it up.
Civilians have always faired poorly in wars, ancient, modern or recent. Rome killed everyone in Carthage and salted the earth. The Mongols sacked Damascus killing everyone, then returning a week later to kill those who had escaped and returned. When the Soviets invaded Germany at the end of WWII 1.4 million women are estimated to have been raped, many dozens of times. Estimates of deaths resulting from rape reach 250,000.
We have seen somewhat of an erosion in the Geneva conventions, which did do something to curtail civilian harm.
The erosion of Geneva convention standards is partly due to a reaction to them. The effectiveness of asymmetric warfare is partly caused by a strategic use of "rules of war" by the weaker belligerent. Basically bringing the war into the civilian sphere restrains the stronger belligerent. Hamas can't fight an open battle against Israel and Iraqi paramilitaries could not fight that way against the US. This forces the stronger belligerent to either forfeit their advantage by using small arms in urban settings and accept soldier casualty rates, shell urban area causing civilian casualties or allow a status quo.
This strategy is completely ineffective against ISIS, for example because they are not restrained by these rules of war.
Rules of war evolve and erode partly with these dynamics. The Geneva conventions are just a modern version this institution and probably somewhere in the middle in terms of effectiveness.
The bloody status quo in Gaza is grafted on to modern rules of war. Israel cannot "win" by applying its full force to subdue or even depopulate Gaza in the way warfare has often been conducted in the past. Gazans cannot fight in the open.
Wars are a bloody affair. The idea that wars should be fought honorably between warriors and leave civilians in peace is not new. Civilians have usually suffered in wars nonetheless. We have never had any kind of deliberate attempt to stop that succeed. We have succeeded in minimizing wars though. The number of casualties from violence is in steep decline. The post WWII period is the least violent in perhaps all of human history.