I think first we need to at least try to define the word love.
I believe the ancient Greeks can help us with this:
Eros - romantic/sexual
Phileo - friends / companionship
Agape - unconditional/spiritual
I haven't really given much thought to the first two types of love, but I think agape love encompasses some of the basic tenets of Buddhist teaching.
The Four Noble Abodes or The Four Sublime States of Buddhism are: loving kindness, compassion, appreciative/sympathetic joy, and equanimity.
Do these ideas not embody the very essence of agape or unconditional love? To practice Zen thinking in real life (as opposed to abstract discourse only) one needs to have an unconditional love of other beings, nature, and one's self. It is difficult to actually verbalize the role of love in Zen, but it seems that love on some level is imperative on the path to enlightenment.
And finally from a martial arts teacher's point of view:
People are illogical, unreasonable, ungrateful, and self-centered. Love them any way.