The major problem with that cosmology is that it raises the spectre of multiple copies of major planar figures, mirror versions of planes, and indeed to coin the 4e design team's own words, it introduces "needless symmetry".
This is one of the major problems that the 3e FR cosmology introduced by having its own cosmology populated by many exact copies of Great Wheel planes that were totally unconnected to the Great Wheel, yet still attempting at times to retain a link to its retconned past by having portals to Sigil, the Great Wheel, etc. In 4e, they really could do better than return to that same problem again.
Needless symmetry? Nah.
4e mentions that there are different worlds such as "the world", Krynn, and Abeir-Toril. It mentions that each world has it's own set of astral dominions (outer planes), but never states that two (or more) worlds couldn't share access to certain astral dominions. In fact, it really doesn't go into detail at all about how Krynn might relate to Toril. Maybe they are alternate dimensions, or maybe you could fly a spaceship between the void to them, or maybe a spelljammer through the phlogiston . . .
Sure, Toril has Lolth living in her very own astral dominion, while in "the world" she has a layer in the Abyss and her different incarnations seem to have different power levels and slightly different backgrounds . . . how is this really any different from how it was in 2e?
Where does Tiamat/Takhisis live? In the Abyss? In Baator? Somewhere else? Is she the head of an evil pantheon or is she a devilish lackey and guardian of a door? (I know, I know, there are some fans who insist the two are completely separate beings that could get together over tea and discuss their favorite evil chromatic dragons).
Point is, Planescape (and Spelljammer before it) created a metasetting overtop of several similar yet distinct settings and never fully answered those questions . . . because, really, it doesn't matter!
But it is not a problem that 4e has that 3e and 2e didn't already have before.
Besides, if we can have an impossible city in an (almost) torus that has no outside and floats over an infinitely tall spire in the "center" of an infinite plane . . . there's room for Lolth being simultaneously a powerful demon, a goddess, and residing in different places all depending on one's point of view (or place of origin).