Solas talks about the Fade absent the Veil. And the codices in the Library in Trespasser make clear reference to the Fade (and to spirits). The Fade wasn't a place, but much like the Weave in D&D it was still a separate and distinct feature of the world.
I agree to an extent, except that what we're talking about is an intricate aspect of the world, not another dimension altogether as now in the story. He verifies the naturally eternal lifespans and magic like the air you breathe, no limitations of interaction with spirits, which again means the spirits themselves were something very, very different before the veil. Otherwise, they'd just have had chaos. So to me, that's closer to a difference between some DA version of Heaven and the mundane world than a description of something more along the lines of a more typical fantasy world, which is closer to what I think most people are envisioning. It's an entirely different paradigm of everyday life. Nature is entirely different. It doesn't entirely jive with Solas depiction of himself as a liberator, but then Fen'Harel is basically the DA trickster deity, like Loki or the DA softer kinder bizarroworld (false) version of a fallen angel that a lot of people believe in, someone who rebelled and cut himself and others off from their paradise, on the grounds that they could freely choose 'freedom' or 'slavery', who's now trying to get back his version of Heaven. You can't trust anything he says. It's his nature to decieve, if that's who he is. Mythal was never particularly nice either, even though she's acted as the catalyst for our protagonists in the series. We know how needlessly cruel she can be thanks to Morrigan, how she was brought up, and Solas obviously didn't rebel against her. Then you have the necessary mutually agreed sacrifice of one required to break the veil. They're not Christian allegory, they're lucipherian. So we can't assume anything benevolent about what happened in Thedas' ancient past regarding them. They're complex characters, don't assume we know so much about them.