Yes and there are still many other races we could learn more of. The Xindi were a very interesting new race that I'd happily see more developed as were the Denobulans. It kills me they were going to go to Denobula in season 5
That's what I would have wanted, more about the Xindi, perhaps a mystery arc about what happened to the Avians! And Denobulans. Their marriages and history give us a great setting to explore, plus I want to see that district Phlox warned Archer against
I actually would've liked it if the Avians, rather than the Sphere-Builders, were manipulating the other Xindi out of revenge for decimating their species.
(Speaking of which, it never made sense that the Avians could build a base on another planet millenia ago, yet NONE survived the destruction of their homeworld).