We are talking about D&D, in the end a good game needs a good DM to run it, if you want to play a game that got rules for every thing including how the DM should act than look no further than WotC advanture board games...
I do not want to play a game that has rules for everything including how the DM should act. That would be impossible in any game with the flexibility and open-endedness of RPGs.
What I want is a game that the DM doesn't have to
fix. The game should be balanced, by its rules. The DM should certainly be free to deviate from those rules, and a big part of the art of good DMing is knowing when to break the rules.
IMHO, what the game need is to teach the DMs to manage those risks, how to build advantures that reward active exploring instead of turteling every 15 minutes, one of the ways to do just that IMO is to build the advanture with a broader scoop in mind so that each combat won't be a grindfest but part of an whole that slowly tax the party resources, couple that with repercussion for not pushing forward.
You're essentially arguing that the rules don't matter, because the DM is there and can fix them.
3.X would be balanced if only DMs learned how to manage the risks of spellcasting. If only every adventure included an anti-magic field, or an angry god that punishes those who abuse magic, then 3.X would be a perfectly balanced game! Heck, just let casters cast any spells they want, as many times as they want, and it's balanced because the DM is there to fix it!
If the DM has to constantly fix or work around a rule,
then it is a bad rule. Bad enough to break the game? Depends. I don't think overnight rests break 4E; they just might break 3.X.
For example, "you come back the next day to find that the kobolds rigged the entrance to collapse when big folks such as yourself walk the floor" or "just when the moon dip into the horizons you feel piercing cold sealing into your bones, you wake up in a start to find that three wraiths have risen through your tents from the crypt bellow"
Stuff like this could be part of the rules. A Fate-point-style system, where the DM gets points, along with the players, would help balance overnight rests.
My point is, what's wrong with encouraging the DMs to build more thought about advantures?
Nothing. The problem is forcing them to warp their adventure design to fix the game balance.