Egan gets your point entirely, and laments that it hasn't been put in service of something better. The best technology in the world deserves to be joined with a great script, not a severely impaired one.
So they use a non-risky script, with nothing objectionable in it.
Once the technology matures you can use a better script. The price of better is that sometimes it's worse, that's why it's a risk. If it was a sure thing everyone would do it, but it's not easy to create something great. You can try, and sometimes you'll make it, and other times you'll flop.
Which is too much of a risk for a new technology - better to have something good enough, with little risk.
Remember: Everyone thinks what they are doing is great. But if you are wrong, and it's a flagship product you are doomed. For example http://en.wikipedia.org/wiki/Heavens_Gate_(film)
How did we get to the point where "Humans are evil, kill them all!" is a non-risky script with nothing objectionable in it?
Joe Valdez at This Distracted Globe has a good review: http://thisdistractedglobe.com/2009/01/01/heavens-gate/ TL;DR version: quit perfecting and ship it!
"Sometime in the next twenty years or so, the technology that enabled Avatar will become cheap enough to risk employing alongside a moderately intelligent script." - it's right there in the review.
It's frustrating when this happens:
Author: A, yet also B. You may think that C, but I'd argue that D makes that untenable.
Commenter: He said A, but clearly C. Another commenter: Hmm, C you say? But what about D? Another commenter: y'all are too swept up in your As and Cs and Ds, have you even stopped to consider B?