It can be useful for circumstances where you want to minimize (or even eliminate) retraction. I've done some cool prints in vase/spiralize mode with large nozzle sizes -- with zero seams, zero retractions, and zero moves over printed surfaces, you can get some really awesome looking prints.
But anyway it was just an example of a scenario where the slicer might not have enough information to know how to not crash the print head.
It also often works better because doing small parts can overheat the plastic. Moving between copies lets things cool down.