I've come up against this many times over. When it stems from over-enthusiasm for using recently discovered features or concepts I've reliably changed a trend-toward-complexity by picking a small section & re-writing it in a simpler/more elegant fashion, then proposing to the author something along the lines of "can we make it _all_ that simple"? The subtle (or not so subtle) creation of a challenge towards simplicity has worked well with coders near the beginning of their career.