I swear to god if I ever see anyone anywhere have something with Lolth's minions moving into the deep caverns below the islands of Arvandor I will scream for a year straight.
And yes, reflections of the world, but then you can argue that the Feywild and Shadowfell being *reflections* is the much-bemoaned pointless symmetry. They don't actually need to be reflections to exist. You can have just a plane of gloom and death and a plane of faerie without having them be reflections.
Hell, the para and quasielemental planes everyone likes to whine about so much were just 'reflections' of a sort. Some of them were a bit of a stretch, admittedly, and a different structure or different planes might have been better, but they all made at least some sort of sense and blended into each other anyway. This is where this touches this and what happens in the middle as a consequence. Yeah, it's infinite. Still touches. Got a problem with that, berk? That's the planes for you. Just 'cause it don't make any sense don't mean it ain't true.
As I've noted before, the multiverse in the old cosmology does not exist for the purpose of being an endless series of reasonably friendly adventure locales. Especially not the elemental planes. They'd go on just fine if every living and/or sentient being in the multiverse disappeared tomorrow. Outer planes? Eventually yeah that's going to cause a bit of trouble, no fresh belief or souls merging with anything. But the inner planes? Doesn't matter a bit.
(I should note that the mere idea of a multiverse where everything is designed to be a Friendly Immediately Useful Adventure Location offends me by coming across as massively insulting and that I don't care for the world axis cosmology and love the old great wheel, and think that the old elemental planes were a neat idea. Do you ever need the Quasielemental Plane of Salt unless you're opening a fast food restaurant in Sigil and need a good source of salt for your fries or have a pressing need to get rid of a massive amount of liquid? No, not really. Does that make it a terrible idea that shouldn't exist? No, not at all.)
At the very least though, the Feydark and Shadowdark need better names that don't make me slam my head on the desk.
And yeah, sooner or later someone's going to come up with and use that first idea in my post. Arvandordark? Get cutesy and call it Darkvandor? Glugh. *shudder*
I don't have a problem with symmetry, it just amuses me in a 'wait what' manner to see... Symmetry when they were complaining about it. <_>;
Whatever. At least Psychognomes are awesome.