Writers about the spiritual life often advocate simplicity. Richard Foster's book, Freedom of Simplicity: Finding Harmony in a Complex World, brings together many of those thoughts and is worth reading.
This anecdote highlights one reason simplicity is important:
A tourist stops at the home of the great Rabbi. Since the Rabbi has such a world renowned reputation the visitor expects to see a great home filled with valuable treasures. However, he is shocked when he sees a bare home with almost nothing in it. “Where are your possessions,” he asks in astonishment. The Rabbi responds, “Where are yours?”; “What kind of question is that?” the tourist said. “I’m a visitor here.” “I am too,” the Rabbi replied.
And simplicity can invite us, lead us, toward the divine:
Too often it is we who won’t let life be simple. Why must we squeeze it and bite it and slam it against what we’ve convinced ourselves are our great powers of reason? We violate the innocence of things in the name of rationality so we can wander about, uninterrupted, in our search for passion and sentiment. Let the inexplicable sit sacred. (Marlena De Blasi, A Thousand Days in Venice: An Unexpected Romance, Kindle Loc. 402-5)
However, complexity is also valuable and essential. Philosophers as diverse as John Rawls and Aristotle have recognized that complexity can add texture, richness, and enjoyment to life.
Theologian Mark C. Taylor recommends embracing complexity as the first component of a post-absolutist theological ethic. The other three elements are promoting cooperation as much as competition, accepting volatility, and cultivating uncertainty. (Mark C. Taylor, After God (Chicago: University of Chicago Press, 2007), pp. 356-358)
Perhaps most importantly and surprisingly, complexity rather than simplicity brings stability to the cosmos and may thus (like simplicity) reveal the presence of the divine. Ecologist Paul Ehrlich has written:
… we have both observational and theoretical reasons to believe that the general principle holds: complexity is an important factor in producing stability. Complex communities, such as the deciduous forests that cover much of the eastern United States, persist year after year if man does not interfere with them … A cornfield, which is a man-made stand of a single kind of grass, has little natural stability and is subject to almost instant ruin if it is not constantly managed by man. (P.R. Ehrlich and A.H. Ehrlich, Population, resources, and environment (San Francisco: Freeman, 1970), p. 159)
Discerning the path of life – an excellent Lenten discipline – consists in some considerable measure of knowing when to choose simplicity and when to choose complexity.