The problem is that only the modern, flashy stuff is being supported by the current copyright owner of the game. So, to each his own, but for now some folks are in the lucky position of liking the current style being sold, while the rest of us wait for features that *will* fit into the style we like to play--whatever that may be.
D&D has always followed what's popular
at the time.
1e had the Monk because Gary took inspiration from Kung Fu the TV show, which was popular at the time. Barrier Peaks was an exploration into Sci Fi because that was picking up at the time (and a test balloon for Traveler). Psionics were added to 1e due to the popularity of Firestarter and other Psionic inspirations.
But all that there was to go on as far as low fantasy was things that had come out before 1e. Tolkein, Conan, Leiber, etc.
Unless
new things are coming out which are Low Magic, Gritty fantasy... then there's not going to be a swing back from the Modern, Flashy stuff - because there's just more Modern Flashy stuff out there, being churned out year by year, inspiring people.
You can only go back to Tolkein and Conan so many times before you've mined all you can.
To put it another way:
A recent poll on this board asked those who were under 25, "What of this list have you read". The list consisted primarily of the stuff in Apendix N (Tolkein, Lovecraft, Leiber, Howard, Moorcock, etc), and some new stuff (Harry Potter, etc).
Very few people under 25 had read more than 3 of the above. But many had read the new stuff.
Along with WotC's market research which says the older gamers are, the less likely they are to buy new books, the easiest conclusion to draw is:
The New Gamers aren't reading the Low Fantasy, they clamoring for gritty, the old stuff isn't popular now of days.
To put it a third way:
WotC is going to go where the money is. Right now, the money is with modern and flashy. They would have to be shown that there is a large hunger for low magic low fantasy gritty 4e stuff. If it isn't popular, then they're not going to waste ink on it.