Paul puts love "above all," showing that love is the epitome of virtues. Here, its importance is as "the bond," something that binds or holds things, like a congregation, together.
Eventually, all groups tend to fly apart. They do not remain united by magic. Generally, a group maintains its unity through a common cause. As each person contributes to attaining that cause, unity is generally served. However, even though individuals expend effort to achieve the cause, frictions arise from a multitude of reasons. Love is the supreme quality that enables the members of the group to maintain unity and keep it from flying apart. This is achieved by each person constraining or restraining himself to act in love.
Interestingly, qualities that we normally think of as being manly—like drive, courage, determination, and aggressiveness—are missing from this list in Colossians 3. Though they are not inherently evil, they play directly into the human ego, frequently resulting in crass individualism.
Because it tends to produce division, individualism is not what Paul is aiming for here. Without strong spiritual control, those traits tend to descend into competitiveness, anger, wrath, malice, dissembling, accusation, slander, and foul talk. These in turn are nothing more than unashamed self-seeking, traits that split and divide.
Each virtue Paul lists is actually an expression of love, traits that make it possible to live in a community. There is nothing weak and effeminate about them: It takes a strong person to resist what comes naturally and do what God commands rather than go along with urges of our carnal feelings. Paul lists love as a separate attribute here to show that it is not limited to the qualities he names.