Over 100 different versions of Avatar were shipped to theaters
hollywoodreporter.com
hollywoodreporter.com
Each type of 3D system has varying amount of cross-eye leak. And the leak varies by color (for some types of systems).
So you need to adjust the color balance to compensate for how much light of each color arrives at each eye. The type of screen, and the size of the screen affects this as well.
Ghostbusting is similar - some light leaks to the other eye, so you reduce the intensity of one side to balance them out.
Product development is making the best product possible.
This was the latter.
[1] http://en.wikipedia.org/wiki/Marketing_mix#Four_Ps
[2] Obviously product development in most fields contains a lot of engineering, design, filmmaking, etc. It's pretty fuzzy, but the kind of stuff in this article--adapting to different screen sizes and languages--is definitely on the marketing side.
When you internationalize a film, there's a bit of "filmmaking" (in that you have to have voice actors dubbing the original film, or you have to have translators rewriting your dialogue) but unless Cameron's more multilingual than I thought, I rather doubt directing all those voice actors and supervising those subtitle writers was any artistic effort on his part. His input was a marketing input: I want my film dubbed and subbed into dozens of languages and shown on half a dozen different screen types. (Cameron's not the first director to film with multiple aspect ratios in mind, nor is he the first to make the artistic call of having different aspect ratios, but I'm sure it affected the filmmaking.)
I didn't mean to take away from his studio's technical chops. Avatar's raised the bar for special effects, distribution, and pioneering new screen formats. But it's not a "labor of love", it's just well executed business.