When Will-o'-the-Wisp was first released, it did not get much attention; however I believe the evolution of the meta game and runner deckbuilding now merits it a second look.
Many runner have limited tutors, typically used to accelerate rig building alongside card draw and recursion from the heap to recover any programs lost to fairly common Corp program trashing. Will-o'-the-Wisp does not trash programs, but puts them on the bottom of the runner's stack. This means that Sacrificial Construct and Fall Guy cannot prevent the effect. Given the infrequent use of Will-o'-the-Wisp, few runners are prepared to combats its effects.
Finally, Will-o'-the-Wisp synergizes well with Ash 2X3ZB9CY, which will allow a successful run with the program-burying effects, but without the opportunity to trash. Architect and Crick allow an opportunity to rescue a trashed Will-o'-the.Wisp from archives to bury once again.