It is often overlooked that de-Nazification and de-Bushidoization was not possible until the will to resist Allied invaders was crushed.
This process took years and required horrific violence to be inflicted on civilian populations, with millions of dead, maimed, and raped.
"Reoccupation" of the Palestinian territories is a simple task for IDF, and it can and no doubt will be carried out nearly bloodlessly by IDF, given the propensity of Arabs to run away.
But crushing the will of the Arabs to resist so that the will of Israel can be imposed on them is not a simple task, and will not be bloodless.
It is probably kinder to expel them than it would be to kill 2/3 of them and brutalize the rest.