Earlier editions of D&D were to a large degree vague, shapeless and formless masses open to interpretation. This came about by happenstance, and it seems like WotC is trying to deliberately recreate that happenstance. I don't think they can, pandora's box has been opened and I don't think it can be closed again now that people's eyes are open. Classic D&D was primarily a dungeon crawl system, but it was vague enough to be clumsily adapted to most anything and was used as such to a large degree because people didn't know any better, or at least because there weren't alternative systems that could deliver. In 2012, we do know better and do have alternatives, having seen an explosion of different takes on d20 thanks to the OGL, more robust non-d20 system choices than existed in the past, and also several more specific and idealized visions of D&D from the OSR and even Pathfinder and 4E.
They seem to be trying to go back to how things were, an "old school" dungeon crawling system left vague on purpose, but without the circumstances that led to the magic.
Okay, you're pretty wrong here.
First off, your argument is fundamentally flawed. You're arguing that older editions were vague and thus rule vagueness is old. Or put another way:
Prior editions were vague.
Prior editions are outdated.
Therefore vague rules are outdated.
That's logically unsound. A is B, A is C, therefor B is C.
Moving on to specifics, you have two main "facts" for your argument. First, that older editions had vague rules. Second, that you cannot go backwards.
The vagueness of older rules is debatable. OD&D was vague but 1e had many very, very specific rules. Meanwhile, Basic D&D (which was published concurrently with 1e-2e) had much more vague rules.
Furthermore, there are a number of very modern games that have vague rules, or rules left open to DM interpretation or ruling. The ENnie award winning Marvel RPG is a crunchy yet vague rule system, left open to creative ideas and improvisation. I can think of far more modern games that are "vague" than crunchy, and even 4e was simplified compared to 3e.
The vagueness or specificity of a game system's rules are independent of the game's age.
Moving on to "you cannot go back". This is highly debatable given the existence of retroclones, let alone their prevalence. There are new clones every year, such as the recently released
Dungeon Crawl Classics game. Watch for it in next year's ENies. And if you count Pathfinder as a retroclone, they're arguably more successful than the modern game.
Many other media revel in going back. Movies and TV shows have remakes or revivals. Video games try to emulate the feel of older games (look at recent Mario games for an example). Franchises regularly reboot or attempt to go back to basics, recapturing some of the feel that had faded. The Batman and Bond films are great examples.
Recreating happenstance is hard, but not impossible. Something being hard is not a reason to give up.
Going "back to basics" is a tried and true strategy. And while not a guaranteed success it can and has worked before.