When we lose theatrical cuts it all becomes a confusing mess.
I think it's a mistake to think of theatrical cuts as "the" cut. Our particular group has been conditioned to think that way because of Star Wars and the relatively unique situation of revisionism; most people would say the theatrical version is of arbitrary importance, what's normally considered important is usually the "director's cut". But it really comes down to audience demand. If an early cut is crappy and of no historical relevance or radical difference, then no one really cares if they can see it or not. I mean, many horror films of significance were widely shown in R-rated versions, but because these versions are not preferred they are never preserved on DVD, because no one cares.
The thing is movies are shown in different ways in different formats and with different characteristics and differences and you can't always have every single minor detail accounted for in its own release, you have to sort of split the odds and single out the one or two most significant and in-demand versions. This is not a new phenomena, though, it's been there since the birth of the medium. Especially for non-contemporary films, there might be two or three versions of the film throughout its original "release" because releases were staggered in waves and the films were tweaked in response to these evolving "tests", like in the case of Heaven's Gate, and it also gave filmmakers to simply change their mind, like in the case of the sound mixes on Star Wars. You have to sort of accept that you aren't going to be able to have official releases of each and every version, or that said releases might only be rare; and in many cases, the tweaking done is so minor that there almost is no point in having two home video versions. Maybe this will happen to Avatar, because at a measily six minutes for a film that is almost 3 hours I doubt many people will really even notice a difference, unlike the extended cuts of Aliens, T2 and The Abyss, which were all 20 minutes longer and of significantly different character. Its the norm to simply let the studio or filmmaker decided on the one version of the film they think is the best or that the audience will enjoy the most, and then if there is audience demand for alternatives they will release those as necessary. I guess we'll have to see if people really can't do without the six minutes of extra footage, because that's really all it comes down to.
Avatar is a strange case though since it was shown in different formats (1.78 and 2.35), and in different mediums (2D film and 3D digital), and in different versions (original theatrical release and second-wave extended version), and home video is its own can of worms since many people can't--or won't want to--view the 3D version, so you sort of have to expect that you might not be able to view every single difference or see the film exactly as it was in the particular theatre you saw it in. I mean, most people probably saw Lawrence of Arabia in the 35mm ratio, but that ratio never has been and likely never will be seen on home video because people are fine with the 70mm ratio, which is what David Lean wanted anyway.
