What have I had out of the cafe car on my few trips...bagels, danishes, the burger, pizza, the wraps (on the NEC).
My impression of it is that though the food could use a quality improvement, it suffices for a trip short enough that one doesn't need to have the same meal twice (i.e. less than 24 hours).
With the upgraded/NEC cafe menu, a single repeat meal is tolerable, and let's face it, not everyone travels end to end. This pretty much covers every single train east of the Texas Eagle.
There's other things Amtrak can add to this menu that can be prepared just with a microwave...think quick oats, etc.