Becoming a Nazirite: Motivation, Meaning, and Merit

There is of course a big difference between lifelong Nazirites such as Samson (Judges 13-16) And Samuel (1 Samuel 1) and the temporary Nazirite in this passage.
Why might one take the vow to become a Nazirite for a period of time?

Rabbi Joseph Dov Soloveichik, "The Halachik Personality," as quoted in Nechama Liebowitz Studies in Bamidbar, p.52
"The religious personality sometimes imagines that afflictions, suffering, fasts, and solitude constitute the media bringing immortal happiness to man.... According to his outlook, the man who withdraws from the world and forgoes earthly and ephemeral pleasures is rewarded with eternal life and a sublime, spiritual existence."

Ramban, Numbers 6:14
Until now he was separated in sanctity and the service of G-d, and he should therefore have remained separated for ever, continuing all his life to be consecrated and sanctified to G-d, as it is said, I raised up some of your sons for prophets, and your young men for nazirites (Amos 2: 11). Thus Scripture compares the nazirite to a prophet . . . Accordingly, [when he completes the period of his vow and returns to ordinary life] he requires atonement, since he goes back to being defiled by the [material] desires of the world

Ramban, Hilchut Nazirut 10:14
Whoever vows to God [to become a nazirite] by way of holiness, does well and is praiseworthy. Of such a person, Scriptures says, His consecration to G-d is upon his head . . . he is holy to the Lord. Indeed Scripture considers him the equal of a prophet, for it says I raised up some of your sons for prophets and your young men for nazirites.

Maimonides, Shemonah Perakim, as quoted in Nechama Liebowitz Studies in Bamidbar
Our Torah, about which King David stated, "The Torah of the Lord is perfect...Making wise the simple", advocates no mortification. Its intention was that man should follow nature, taking the middle road. He should eat his fill in moderation, drink in moderation. He should dwell amidst society in uprightness and faith and not in the deserts and mountains. He should not wear wool and hair not afflict his body. On the contrary, the Torah explicitly warned us regarding the Nazirite.

Rambam, Hilchot Deot 3:1
A person may say: “Desire, honor, and the like are bad paths to follow and remove a person from the world, therefore I will completely separate myself from them and go to the other extreme.” As a result, he does not eat meat or drink wine or take a wife or live in a decent house or wear decent clothing . . . This too is bad, and it is forbidden to choose this way. Whoever does so is called a sinner. Indeed G-d says about the Nazirite: “He [the priest] shall make atonement for him because he sinned against the soul.” The sages said: If the Nazirite, who only abstained from wine, needs atonement, how much more does one who abstains from all [legitimate pleasures] need atonement. Therefore the sages commanded that a person only abstains from things forbidden by the Torah alone . . . Concerning these things and others like them, Solomon commanded, saying: “Do not be overly righteous or over-wise. Why should you destroy yourself?" (Eccles. 7:16)

Taanit 11a:14-16
Samuel said: whoever indulges in [voluntary] fasting is called a sinner. This is in accordance with the view of Rabbi Eliezer Hakappar Berebi, who stated: What is the meaning of the phrase (Num. 6: 11), and make atonement for him, because he sinned against the soul (usually translated as “by coming into contact with the dead”). Against which soul did he sin? We must conclude that it refers to denying himself the enjoyment of wine. From this, we may infer that if one who denies himself the enjoyment of wine is called a sinner, all the more so one who denies himself the enjoyment of other pleasures of life. It follows that one who keeps fasting is called a sinner.

Ibn Ezra as quoted in Nechama Lebowitz Studies in Bamidbar, p.57
He shall not make himself unclean for his father or for his mother, for his brother or for his sister, when they die; because the nezer "crown" or "consecration" of his God is upon his head (Numbers 6:7). Some maintain that the word Nazir is from the term nezer, meaning crown, adducing proof from the foregoing passage, which sounds very plausible. Know that all human beings are servants of worldly desires, and whoever is free from these desires is a king who has, indeed, a crown and royal garland on his head.

Rabbi Moses Isserles, as quoted in Nechama Lebowitz Studies in Bamidbar, p.58
...spiritual healing corresponds to physical. Man must divert his evil inclinations from the extreme to the middle way. This is the basic idea of the Nazirite when he abstains because he observes that he has a weakness for worldly pleasures. He must go to the other extreme, in order to attain the middle way. Therefore, the Torah states, "he shall be holy" (Numbers 6:5), since the holiness of the Nazirite will only really be in evidence, later on, after he has completed the days of his Naziriteship. Only then will he have attained the middle way, not at the time of taking the vow, when he had sinned and was imperfect. This is the meaning of the statement "and makes atonement for that he sinned..." This is because the abstention of the Nazirite is evil in itself since all extremes are bad. The Nazirite was only commanded to abstain in order to achieve a good purpose, the attainment of a more middle way.

Rabbi Lisa Grushcow, D'var Torah on ReformJudaism.org
So how might Nazirite practice be explained, in light of our knowledge about addiction? We know that for recovering alcoholics, a sip of alcohol has a different effect than it would on anyone else. The Rabbinic concept of “building a fence around the law” thus could have a very tangible meaning: that we avoid not only alcohol but also ingredients used to make it, as a way of separating oneself from temptation. Likewise, avoiding contamination by the dead could be understood as distancing oneself from associations in one’s previous life as an addict — a path that can lead to a return to addiction, and ultimately, to death. And not cutting one’s hair? Perhaps that could be seen as a commitment to humility, to valuing the integrity of internal choices over external appearances. Also, as some commentators suggest, the fact that Nazirites can be recognized as such allows others to help them on their paths by reminding them of their commitment. I never would have come to this perspective, were it not for a congregant who learned this passage at Torah study one Shabbat morning, then approached me to ask about the Nazirite vow as a component of her own recovery. After more study and discussion, she decided to go forward with a private vow in front of the ark. When asked to describe her choice, here is what she said:
I am choosing to become a Nazirite for several personal reasons. First of all … being an alcoholic, this commitment I have already made to stay sober will also help keep me connected to God, and allow me to include my spiritual beliefs and being a Jew as part of my commitment to sobriety. Also, making commitments for a year not to cut my hair and not to consume any grapes or grape products, will remind me that I am a Jew and how important my beliefs in God are on a daily basis…. This is not for status or to be better than anyone. This is to help me to become a better me.