World Communion Sunday began in 1940, a time when most Protestant churches celebrated Communion quarterly at most, and so may rarely have celebrated on the same day. Today, the vast majority of Christians worldwide celebrate Communion weekly; and most Protestants celebrate at least once per month, most frequently on the first Sunday. The need to highlight this day as “one time when we are all celebrating together” has thus subsided. The more salient focus for the celebration now is on supporting ministry issues we share across multiple denominations across the globe—such as education for persons of many cultures worldwide.
(also to note) ... the Ecumenical Cycle of Prayer was created by the World Council of Churches to enable Christians everywhere to pray with and for the church and the world, for every nation on earth, throughout the year.
On World Communion Sunday it is also appropriate to consider all those we may inadvertently “excommunicate” because they are unwillingly absent, marginalized, or outside our comfort zones.