One of the great difficulties we have is making a clear distinction between people and the ideas that they espouse. While one might reject an idea, we may not reject the person who espouses such. This is true even of ideas that we find offensive or heretical. Judaism goes one step further and demands that we even separate the actions of an individual from our feelings towards that person. In a famous Talmudic passage Beruriah, the wife of Rav Meir chastised him for his anger at the local troublemakers, anger that should have been directed only towards their actions. While at times evildoers must suffer the consequences of their actions, such punishments are meted out with great pain and regret. Thus a court before implementing a death sentence must stay up all night looking for some justification that might allow for leniency and if none can be found the court members must fast on the day of execution. And once a punishment is given the perpetrator is to be regarded as your "brother" and be accepted as such. This is at odds with western mores where "sins" committed years ago are often used to discredit one's reputation.
Perhaps no better example of separation of person from deed, can be found in the halachic obligation to give charity, visit the sick, bury the dead of those who are idolaters. When one considers the Jewish view vis a vis idolatry coupled with the fact that idolatry was understood to include moral degradation this ruling defies belief. Nonetheless such are the teachings of Judaism that while we despise idolatry we must help its practitioners. The importance of helping even those whom we rightfully or (almost always) wrongfully hate, is codified in the law that given a choice to help your friend to unload his donkey and thereby decrease the suffering of the animal or your "enemy" to load his animals it is the enemy who must be helped. Our Sages long ago understood that which modern psychology has shown, that by helping others we develop a concern for them.
Over and over again we are instructed to be kind to strangers because we were strangers in the land of Egypt . While the concept of not letting our past allow us to hurt others in the present, is readily understood, if not always implemented, the Torah demands much more. "Do not despise the Egyptian, since you were an immigrant in his land" (Devarim 23:8). What an incredible command. The Egyptians, the descendants of those who enslaved and killed us; the nation whose sins were so great that "there was no house where there were no dead" (Shemot 12:30) are not to be hated by us. This despite the fact that we are to utterly reject the Egyptian lifestyle; "Do not follow the ways of the Egyptians where you once lived" (Vayikra 18:3). Moreover it was the Egyptians who were the first to come up with a final solution to their Jewish problem - yet the Torah wants us to focus on the fact that it was our residence for hundreds of years. It is precisely in order to instil in the departing Israelites more pleasant memories of the Egyptians that some commentaries explain the divine command to "let each man request from his neighbour and every woman from her neighbour jewels of gold and jewels of silver" (11:2).
Interestingly enough, this command is recorded not just after the exodus but in Sefer Devarim , 40 years later, to the children of those who dwelled in Egypt . To expect those who actually suffered at the hands of Egyptians not to harbour hate is perhaps unrealistic; the healing would have to wait a generation. And full reconciliation would have to wait even longer; "Children born in the third generation may enter the congregation of G-d (in marriage)" (Devarim 23:8).
With this background we can begin to appreciate why Moshe Rabbeinu could not bring the first three plagues upon the Egyptians. As Moshe was saved from certain death by the Nile River , it would be most inappropriate for him to cause the water to turn to blood or frogs to emerge from it. Similarly the third plague emanating from the earth also had to be brought by Aharon as it was in the earth that Moshe buried the Egyptian he had killed. We should feel no remorse for the plagues and death that the Egyptians suffered; their fate was well deserved. Nonetheless as a beneficiary of the Nile , Moshe was not to be the one to use it to cause harm.
It is very painful to witness Jews who become more observant later in life criticize and denigrate the religious ideology in which they were raised. Whether or not their criticisms have some merit is irrelevant. Worse still is when new found ideology leads one to personally shun or attack those whose views they no longer share. We must remember that all people, even the Egyptians, were created in the image of G-d.