I really don't think those techniques are actually "better" - they are just different. They are better for achieving a different end point.
There is a pervasive idea that there exists some sort of "ultimate" roleplaying paradigm; that there is some 'perfect' game style that every group should either play or, if inexperienced or otherwise handicapped, aspire to.
I didn't mean to imply that there was "one true way". There are certainly many ways to become a 'good' DM. And it is also quite right that the DMG provide a set of guidelines that will enable the newbie to start DMing, and to run a game competently.
But if the DM never moves beyond the guidelines offered in the 4e DMG, all they can ever be is 'competent'. Although there are many ways to become 'good', simply robotically following the guidelines offered is not one of them. Most DMs will eventually seek to move beyond this point (or they and their groups will lose interest and drift away), and at the moment they are largely unsupported in doing so.
If the group wants a slightly different game than that primarily supported by the rules selected, there is nothing very wrong with modifying or "drifting" those rules to match what they really want more accurately. There is a danger, however, that those with strong desires for a different game agenda than that primarily supported by the sselected system will, after accepting the original game proposal, set out to 'drift' the game more to their desired agenda without transparency or reference to the rest of the group. It's a sort of "bait-and-switch" - especially if the GM is the one drifting the game.
Thing is, they do that
anyway. That's just the same issue as the "killer DM", or other such behaviours - you can't write rules to prevent people being jerks.
But you
can make DMs aware of the different styles, equip them to achieve them, and also
advise them to communicate with their group about whether this is something that actually should be done. Also, you can warn DMs that some players may themselves try to 'drift' the game, and how to deal with that situation.
At the moment, this is all largely unsupported. I know how to do it, I daresay you know how to do it, but does a DM who came in with the 4e DMG and for whom that's all he knows?
I perceive fiat decisions, houserules and creative rules "interpretations" as mainly signs that the RPG system as written does not perfectly match someone's desire for style or focus of play.
No system as written will ever
perfectly match the styles of everyone at the table; all will need some adaptation to really sing. Worse still, people's preferred styles will drift over time. Far better to support the group in adapting the game (and evolving it as necessary), rather than sticking with "here's what our game does, and nothing else."
Bear in mind that if D&D had never looked into other styles, there would be no Dark Sun, no Spelljammer, no Ravenloft, no Eberron... oh, and no 4e.
Giving more power to the GM in this milieu may either work out well - if they successfully gauge the desires of the group and drift towards that - or badly - if they either gauge poorly or ignore the desires of the group as a whole. The pitfalls in this - especially if the group is split in its desires - are manifold.
That's why you start with the baseline, to get DMs to 'competent', before trying to take them on to 'good'. Then open your 'advanced' book with "The Importance of Communication", "Dealing with Problem Players", and "How to Avoid Sucking as a DM".
Then start empowering them.
But, again, you're not actually giving DMs power that
they didn't already have. To a very large extent, the DM already sets the tone and parameters for the game. The players have an impact, but not to the same extent, and often their santion is limited to the ability to walk out. So if the DM decides he's going to 'drift' the game in a particular way, he doesn't need the 'permission' from some book to do it. Thus is makes sense to provide guidelines to at least try to help him do it
well, rather than just ignore it and pretend it doesn't happen.
Gauging a group's real desires is incredibly tricky business (ask any politician!) and will often lead to a "best compromise" that actually doesn't meet anyone's desires perfectly. This is why I prefer published systems to be clear what they set out to support, and to do it well. At least, that way, all those joining the game should have a reasonably clear picture of what "class" of game they are joining. Games that try to attract everyone will often, I think, store up problems, as "competing" sub-groups try to "drift" the game their way. I saw this a good deal in earlier editions of D&D.
In a perfect world, there would be games to cater to every playstyle, loads of players to go around, and everyone could just play the game they wanted. We don't live in that world. As it is, it is much easier to find players for 4e D&D (or perhaps Pathfinder) than for any other game, and it's also easier to find players willing to play D&D in a 'storyteller' style than it is to find them willing to play some other game tailored for that style - people are more flexible to changing style than they are to changing system.
So, if D&D is the baseline, then it really should be a broad church. And there is absolutely nothing wrong with them providing one book that provides support for these styles
as an option. Otherwise, you're consigning it forevermore to be nothing other than "kill monsters, take their loot; repeat".