It wasn't a commandment when it was given. But it IS a commandment now. And no, it's not a commandment merely because it's been "blown out of proportion"...it was made a prerequisite for entering the temple via inspiration to the Prophet. As Mormons, we believe continuing revelation to God's Prophet.
EDIT:
The Word of Wisdom became a binding commandment when Heber J. Grant was prophet. But the importance of observing the World of Wisdom was stressed increasingly by each prophet leading up to Heber J. Grant.
Observe the following trend from Brigham Young to Heber J. Grant.
-Brigham Young-
"The spirit whispers to me," said Young in 1867, "to call upon the Latter-day Saints to observe the Word of Wisdom, to let tea, coffee, and tobacco alone, and to abstain from drinking spirituous drinks." In this same year, Brigham Young referred to the Word of Wisdom as "the word of the Lord," and explained to the members that although they had a great many privileges, indulgence in liquor and other injurious substances was not one of them.
-John Taylor-
Two years after taking leadership of the church, according to one researcher, John Taylor received a revelation designating the Word of Wisdom as a commandment.
-Wilford Woodruff-
By 1894 Wilford Woodruff became President of the Church and spoke forcefully to the members about Word of Wisdom compliance. With the increasing concern over observance, some leaders began to question whether those who did not fully follow the Word of Wisdom should be allowed to attend the Temple. In the early 1900's bishops were asked to consider each situation on its own merits since there was no rigid rule for each case. Recognizing that it would be a hardship for the older men--who had become addicted--to abstain from tobacco in order to enter the Temple, the First Presidency decided in 1902 that such members "should at least be willing to curtail themselves as much as they possibly can, and promise to cleanse themselves from the tobacco odor and not to use it at all the days they do work in the temple."
-Joseph F. Smith-
Joseph F. Smith, fifth President of the Church, felt "the reason...why the Word of Wisdom was given not by commandment or constraint was that at that time...it would have brought every man, addicted to the use of these noxious things, under condemnation." He reasoned that a merciful God would give individuals a chance to overcome undesirable habits before bringing them under law. Nevertheless, Joseph F. Smith felt that it was time for stricter observance. In 1902 he "urged stake presidents and others to refuse recommends to flagrant violators but to be somewhat liberal with old men who used tobacco and old ladies who drank tea. Habitual drunkards, however, were to be denied temple recommends." As demands for observance increased bishops were advised to no "'longer tolerate men in presiding positions who would not keep the Word of Wisdom.'" By 1906, in keeping with the increased emphasis on abstinence, the First Presidency and Twelve substituted water for wine in the sacrament in their temple meetings. Seven years later, the First Presidency instructed the President of the Salt Lake Stake, not to call or recommend missionaries who did not observe the Word of Wisdom."
-Heber J. Grant-
Five years later Heber J. Grant became Church President, and in 1921 adherence to the Word of Wisdom was made a requirement for admission to the Temple.
(info above is from) http://www.fairlds.org/FAIR_Conferences/2000_Up_in_Smoke.html