Many governments are dictatorships or autocratic. Some are democratic. I dont think it matters. You have the same responsibility to civilians regardless of the form of government.
> carte blanche to raze the city
Generally not. But you can certainly destroy buildings used for military purposes. Where this conflict falls on this scale is pretty unclear thus far.
> eliminate its civilian population
Definitely not. Israel has not done this.
> displace ... its civilian population?
Maybe. There are certain circumstances under the geneva convention where this is allowed, and it seems likely the criteria was met in this conflict. You of course have to let them back once the fighting has subsided.
For cases where the original person is now dead (1948 was 75 years ago), i think its reasonable that that person's descendents should split appropriate compensation.
What im getting at here is - if someone was driven out and owned a 1 bedroom apartment, they are only owed a 1 bedroom apartment. If they had 50 grandchildren they are still owed only the single apartment not 50 apartments, one for each heir.
The other big issue is this was 75 years ago. Much of this property probably doesn't exist anymore. I think due to pure practicality, cash compensation would have to be the way to address this issue.
Still, there are levels of blame and the current situation. The Palestinians in Gaza are held hostage by an evil organization that keeps escalating and using ceasefires to increase armaments. I would love it if Netanyahu would be out of office right now and someone "competent" were running things. But this is the position we're at.