The land of Israel has been developed in such a way that it has become completely different from what it was one century ago, and there is no doubt that its previous owners could have never succeeded to do a similar development, due to a combination of lacking both the financial means and the skilled labor capabilities.
While I believe that returning the land would be unjust at this time, I also believe that the never-ending war between Israelis and their neighbors can be stopped in only 2 ways, one of which is not acceptable in the modern world and which would bring eternal shame on Israel if they would ever succeed to realize it.
The second option is for Israel to do the same that Israel has demanded and has obtained from states like Germany. This means that Israel should admit that they have occupied the land by force and they should repair this by paying a just compensation to the remaining descendants of the former inhabitants, exactly like Israel has received from countries responsible for the oppression against Jews during WWII.