I honestly don't believe those two things are at odds. The initial design includes a number of presumed rules for first time play. House ruling comes in later with changing preferences. You and I've played before, so it's done immediately.
Reynard said:
Is the individual group house-ruling something to meet their preferences irrelevant to the larger gaming community, including these new DMs?
Well, yeah. My house rules are pretty much irrelevant to everyone but my friends at the table. Unless you want to hear about my character

The community's gonna share their own home rules with each other pretty much regardless of publisher intent.
Is consistency from one table to the next, whether in a basement or at a con, important in any way, or even viable?
No, except in special cases. Tournaments at Gencon use the same game rules in an endeavor for fairness across teams. In other ways, it may just be a market flooding technique, but that's not really my thing. I don't know.
How does the idea of the VTT figure into it, which could potentially get a lot more people playing with a lot broader cross section of gamers?
I'm guessing it will be like most internet games... a mess. Not that the system won't work (that's a programming issue), but that people will run the games they want.
The kicker is: will the software allow for customization?
Will it include the ability for community constructed plug-ins, add-ons, and extensions?
Will it allow licensing for these in parts of its code enabling commercial enterprise by other software companies?
Will it license parts for non-commercial software developers like Firefox does?
Will it go so far as to open source all or part of its' code like the in the free software project?
(I'm gonna guess no on the last one)
Certain things will always make the game harder to play online than off. It remains to be seen how assumptive the game board will be for DDI and how the design (not just the internet) will restrain play.
Actually, I'll start a new thread on this.
And finally, what about the "advanced DM"? Do you think the intent is that more advanced Dming techniques will be the subject of things like the DMG II? Or will the DMG II simply be a book of new crunch/updated and converted old crunch?
Advanced DMing would be like texts for high level art classes. They'll be more about difficult techniques, explorations behind why the basics work, how to find one's own voice, altering the rules while understanding their purpose, modifying printed modules and supplements to fit one's own game. Plenty of etc's on that.
In essence, they'll be more about allowing the DM/group to run/play the game in his/her and their own way. Paint by numbers only works in the beginning when creating a finished work is most important. House ruling is really saying the game is ours.