Reduce or remove WooCommerce 2.5 minimum password strength requirement for creating a user account. Warning: Use at your own risk.

functions.php

<?php
/** 
 *Reduce the strength requirement on the woocommerce password.
 * 
 * Strength Settings
 * 3 = Strong (default)
 * 2 = Medium
 * 1 = Weak
 * 0 = Very Weak / Anything
 */
function reduce_woocommerce_min_strength_requirement( $strength ) {
    return 2;
}
add_filter( 'woocommerce_min_password_strength', 'reduce_woocommerce_min_strength_requirement' );