Positive character traits serve as a foundation for the commandments of the Torah. It is inconceivable that a person observe the Torah's commandments if he lacks positive character traits. Such traits serve as an introduction to the Torah and its commandments. Without these ingredients it is impossible to successfully establish any sort of society. Even within gang mobs certain fundamental guidelines of law and justice and mutual trust need to be upheld. Without such, no group can survive.
Rabbi Chaim Vital, in his work "Shaarei Kedusha," expands upon this idea:
"Positive or negative character traits are like the throne and foundation and root of the sublime, rational soul upon which the 613 commandments are dependent. Indeed, they (these traits) are the most essential preparatory factor in as far as the fulfillment or non-fulfillment of the commandments is concerned. And because they serve as the foundation of the fulfillment of the commandments, negative character traits are worse than the transgressions themselves.
"Hence, it is possible to understand the words of our Rabbis of blessed memory: 'Whoever loses his temper is seen as having practiced actual idolatry,' and idolatry is likened to the violation of all the other commandments combined, and the Sages say, 'One who has bad manners is considered a heretic, and such a person deserves to be uprooted like an Ashera Tree.' We find, then, that it is more important to distance ourselves from negative character traits than to fulfill positive and negative commandments, for once a person attains good character traits, he can easily fulfill all of the commandments."
Rabbi Chaim Vital continues: "This allows us to understand otherwise puzzling statements made by our Sages of blessed memory concerning good traits: humility and contriteness lead to Divine inspiration, and cause the Divine Presence to dwell upon a person. And Elijah the Prophet says, just as the Torah is not understood by one who is irritable only reveal myself to one who is not irritable. They did not mention Torah commandments, but positive character traits. Direct your attention to these words of mine and you will certainly succeed."
Rabbi Moshe of Coucy, author of "Sefer Mitzvoth Gadol" which enumerates the 613 commandments, tells of a certain voice he heard while dreaming one night: "You forgot the most important matter, be careful lest you forget." He then looked closely and found that this dream was referring to the words of the Rabbis: Where do we find a warning against those who have bad manners? From the verse, "[Be careful lest you forget God your Lord...] But your heart may then grow haughty and you may forget God your Lord" (Deuteronomy 8:11, 14). And wherever it says "be careful lest" or "do not" there is a negative commandment, and from here there is a warning not to be proud, and this is the important matter that he forgot.
Hence, as noted, good character traits constitute the foundation for the performance of commandments, and without such traits it is impossible to uphold the commandments. All the same, it is important to remember that they are only preparation for the commandments and that the commandments themselves constitute the highest level of perfection. It is impossible to stop at good character traits, the performance of justice, and the love of kindness. These are mere human imperatives. The commandments are superlative Divine tutelage which elevate the Jew to an exalted level, for one cannot approach the Almighty but via the actions which He Himself commands.
In sum, good character traits, justice, love of kindness, humility, a good heart, love of God's creatures, a positive outlook – all of these qualities constitute a necessary foundation, and they are the substructure upon which one constructs the complete edifice, complete service of God - the fulfillment of God's precepts.