"Lot Rot" covers a lot more sins than dead batteries. A year older model has all the features of a year older model, sometimes it has had body damage that has been repaired, an older model is usually missing options that are highly desirable (like advanced safety gizmos), sometimes they acquire residents (insects and rodents) while waiting to be adopted by a forever home.
If you can purchase a year older model for significantly less than a newer one and it has what you need, and if it has not been damaged in any way, get it. If you drive a lot of miles per year, when you go to trade it in or sell it, it will appear to have average miles. If you buy a newer model and drive a lot, prospective buyers will look down on your van.