Who says that's what I'm having trouble understanding? I never once asked that question.
Well, then I am having trouble understanding, because it seems to have come up.
My question is, was, and probably yet shall be: why the sudden high visibility of sandboxes? A correllary to that could be why do the sandboxers continue to put forward the implied--if not explicitly stated--notion that a sandbox approach is the best approach and the default "mode" of D&D, or even roleplaying as a whole, when clearly there are vast swaths of groups out there for whom the approach would fall completely flat?
(1) Because, when people hear the concept, they are interested. When they try the concept (with a good sandbox GM) they like it more.
(2) It is one of the most obvious things that tabletop games can do better than computer games.
(3) Some people (perhaps some
vocal individuals or perhaps
vast swaths of groups) are looking for alternatives to the tenets of AP-style D&D, which has grown stale for them. And,
(4) It is not at all clear that there are
vast swaths of groups out there for whom the approach would fall completely flat. It is, however, clear that this is true for some
vocal individuals.
Even in this second, more polite version of the thread that we've migrated to, I still feel like there's a vibe running through if of, "well why don't you like sandboxes?" and if I describe some pitfalls of sandbox play, I get told that I'm just doing it wrong. Or that my groups must lack imagination. Or whatever.
Well, if there is really a "sudden high visibility of sandboxes", and you really are concerned with why this is the case, then it makes sense that you accept the word of those involved in said "sudden high visibility of sandboxes" as to what sandboxes are, as well as why they are interested in them, and why they promote them.
When you argue about any of the above, it makes the initial question seem to be something other than what you are actually interested in.
People have been fairly explicit about this; you shouldn't still be wondering.
People have attempted to answer your earlier question & correllary. AFAICT, it was answered pretty accurately on the first page.
RC