It depends on what type of wood foundation you are talking about. There are houses here in South Texas that were built on cedar foundations that will outlast the house. I grew up in a cedar foundation house that was built in the late 1800's. The cedar posts rest on limestone rocks and are protected from the elements by the house. This type of foundation is especially well suited to our expansive soils dirt. It contracts when it dries and expands when wet which can crack a slab foundation. I guess the bottom line is. No, having a wood foundation should not automatically make it a bad investment. As always, you should have it inspected by a trained professional to make sure its up to snuff.