I suppose I never really answered the question...just posted a picture of someone else badass 4Runner!
I think that colors, just like anything else come and go in cycles. That deep green color was very common in the 90's and early 2000's, but faded away like any trend. Right now, green is still a hot color...but just in a different shade, and that shade happens to be retina searing green that you see on every super exotic car. Green will come back eventually, but it may be in the coming months, maybe in 15 years.
Overall, I do have to agree that the colors are a little boring for the 4runner line-up, besides the TRD Pro specific colors (Inferno Orange, Quicksand, Cement, Cavalry Blue). They definitely could use a green! I personally have a red TRD Pro because the Cement was essentially a $10,000+ option because the crazy mark ups.