I Believe the Trend Was Caused by All the Things I Believed Before I Investigated the Trend
This is so common that there ought to be a name for it (perhaps there is and I just don't know it): Writer does a story or study on some trend, in this case the downfall of the enclosed shopping mall. In each case, the writer discovers that such malls died because of ... all the things the writer already holds dear. If the writer hates American consumerism, then the fall of such malls is a backlash against American consumerism.
It is interesting to note that all of the ideas quoted are demand-side explanations, e.g. why might consumers stop going to large enclosed malls. And certainly I find the newer outdoor malls more congenial personally, but this can't be the only explanation. Here in north Phoenix, I can see the dying enclosed Paradise Valley Mall out my window, but just a few miles away is the Scottsdale Fashion Square, a traditional mall that appears to be going great guns. Ditto the Galleria in Houston. Perhaps part of the answer is that enclosed malls were simply overbuilt and that people are willing to drive a bit to get to the best enclosed mall in town rather than a smaller version closer to their home (certainly Mall of America made a big bet on that effect).
But it also strikes me there are supply side considerations. The mall out my window is a huge waste of space, surrounded by parking lots the size of a small county. And it's just retail. Modern outdoor malls allow developers to mix shopping, living, and office space in what looks to my eye to be a much denser development. All these malls have stores on the ground floor with condos and offices up above. To my not-real-estate-trained eye, this would seem to increase the potential rents in a given piece of land and provide some synergies among the local businesses (e.g. office workers and residents eat and shop in the mall shops). In some sense it is a re-imagining of the downtown urban space in a suburban context. This is ironic because it is something urban planners have been trying to force for decades and here comes the free market to do it on its own.
People also like going to newer facilities. Just ask hotel owners. If owners do not totally refresh a hotel every 20 years or so, people stop visiting and rates fall. The same is true of gas stations and convenience stores. When I worked at Exxon briefly, they said they budgeted to totally rebuild a gas station every 20 years. So it is not impossible there is a big supply-side explanation here -- if people are reluctant to go to establishments over 20 years old, then visitation of enclosed malls should be collapsing right about now, 20 years after they stopped being built. A shift in developer preferences could be a large element driving this behavior. I don't insist that the supply side and real estate incentives are the only explanation, but I think they are a part of it.