Hmmm. I don't think it is restrictive, depending on how you look at it. Study of the Torah and self-realization are the same thing, the will of the creator and all that. One need not study Kabbalah for self-realization however, even having children is a form of it. Now, were I to invoke pretension, I would say that a clue to why this is appears in Genesis and Proverbs, in that a certain type of angel, the cherubs (כרובים) are mentioned only twice in the Torah, and later on in the rest of the bible pretty sparingly. The first time is when god expels Adam and Eve from Eden, putting a cherub at the gate with a flaming sword. The next time we see cherubs, they are the angels guarding the Ark of the Covenant.
Now, in Proverbs 3:18, in speaking of the Torah itself, we have a verse saying "it shall be as a Tree of Life to all who hold it." The implication is that attainment is possible through being fully attuned to the will of the creator, and the will of the creator is the Torah, and this is what the flaming sword is guarding. I'm explaining this on one leg, but it has to do with immortality, subjectivity and the original Tree of Life, which from a story point of view is pretty mysterious, being mentioned about twice in the expulsion story. I recommend you read Serpents of Desire
, a series of essays by Rabbi David Fohrman. Any mythology should be analyzed on its own terms, and this is what he does, although I disagree with some of his more social conclusions.
In more practical terms (if you can call it that) there is a tradition of practical magic in Kabbalah, although from my understanding it is more of a fringe thing. One of the more famous examples is a Kabbalistic curse placed on many Israeli leaders (among them Yitzhak Rabin) denying the subject of God's forgiveness (even theologically, this premise presents problems), called the Pulsa diNura
. Whether it works or not is debatable, since although Rabin himself (and consequently the peace process itself) was indeed assassinated, there has seldom been a Prime Minister of Israel that has not pissed off the religious orthodoxy in one way or another and has not had this curse placed upon them. Most do, it's practically considered a rite of passage, meaning you have "arrived." Rabin is hailed as proof of the curse's success, but nobody talks about all the times it didn't