Except the basic premise of epic wands is all wrong. A rod and wand do similar things. If want a wand that casts 9th level spells, all you need to do is make it a rod. That is why there is an Epic Rod feat but no Epic Wand Feat. Wands are limited to 4th level spells but rods aren't. Plus you can put metamagic components on rods, which you can't on wands unless you adhere to the level limit. Plus, when you create a wand it has 50 charges. When you create a rod, they generally don't. Plus ANYONE can use a rod.
I understand the aesthetics of wanting a wand that does what a rod does, but it's kinda silly when you can already DO all that.