BryonD said:
You're certainly correct here.
I'm guilty of it in many respects. I seem to be in a limbo between seeing that it doesn't have to be that way and actually implementing a wider view.
Ditto, here. I wouldn't be averse to a lower-level planar based game, but it always feels like it's not "getting justice" to me. Having a rich environment is one thing, but 90% of the inhabitants of the Great Wheel Outer Planes could slash mortal low-level adventurers to ribbons in a single fit of pique on their home territories (like the 'loths, Tanar'ri, and Baatezu that Shemeska's description mentions).
In a neutral ground (like Sigil) these Daemons, Devils, and Demons would be fun to interact with for sure, and negotiations on their home planes would be the most tense thing imaginable (and thus even more fun!

) because one wrong word or insinuation will probably mean death (or a stiff fight, at the least).
I love ideas like the Iron City of Dis, like Pluto's realm in Hades (whichever plane it's supposed to be), places where death is not assured, but it's still a hostile place to be, as the bastions of safety that extraplanar adventurers can cling to when being "pilgrims in an unholy land."
But then, in the end I'm of the "old school" as Psion puts it, and cling to the "pilgrims in an unholy land" view of Outer Planes adventuring rather than the more "cosmopolitan" view, for lack of a better term. I find it hard to put something "one gate away" as a means to an adventure, until the party has an ability to make those gates themselves, and even then plane shifts and the like don't mean an exact location, but travel and adventure are still involved.
If and when our group resumes our Eberron campaign (hopefully late this year) some planar expeditions may be written in because the PCs are powerful enough for it, and it can pose some interesting problems for them to solve - things that can only be made in certain places, or seeking people that can only be found... elsewhere.