I'm sure Lucas wouldn't mind because, well, he's got no saying in the matter anymore.
Thanks! I think it actually is a great idea.
Because that would break the Lucas approved timeline of when they appeared
The Chiss are already in the game and shouldn't be here yet. Why not add them? This could be their first expeditionary force that comes to this part of the galaxy, a first legion if you will. The rest come later (in the approved time frame).
I hate the Yuuzhan Vong with a passion and cannot wait until this stupid "ultra-evil overlord that is way more advanced than anything else" race is purged from the canon in the new trilogy.
Why not fell them by your own hand?