Aristocratic Freedom
A common denominator of these rules, points out Rabbi Aharon Halevi in his classic Sefer Hachinuch, is to inculcate in these slaves on the threshold of freedom a sense of aristocracy. They must view themselves not as mere slaves escaping bondage but rather as princes chosen by G-d to soon receive His Torah and be elevated to the status of "a nation of kohanim and a holy people".
There is an important lesson here for all of our people today in Israel and throughout the world. If we are privileged to enjoy freedom as Jews almost everywhere and to even have our independent land, we must behave as responsible aristocrats rather than as hedonists pursuing only physical pleasures and unfettered freedom.
If we internalize this Torah message of noblesse oblige we will deserve to enjoy the noble freedom of Israel forever.