The thing is, the idea that IF went "back to da rootz" on Foregone is a fundamentally flawed perception as nothing on Foregone relates to their roots. It doesn't relate to any of their back catalogue because they didn't sound like that at any point in their career. At best you could say SSoD has some ATG influence, but that isn't In Flames, and Great Deceiver has some moments that would fit on Come Clarity, but not the song as a whole.
It's not a back to the roots album, it's just an album where some songs are a bit heavier than stuff they've been doing recently. They were never a heavy band to begin with - in the context of the metal sphere, anyway. They were always way more about beautiful melodies, and you hear that when any of their old stuff is played on piano, it sounds amazing. I doubt Cannibal Corpse would transfer in the same way.
Besides of which, outside of the singles the tracks are basically the same fake and boring shit they've been doing for a while now. The singles would have made for a somewhat worthwhile EP, but the rest of the songs don't add much. Pure Light of Mind is actually okay, sans the stupid autotuning on the vocals, but what part of that exactly is back to the roots?
In regards to Sonata Arctica, a couple of songs from the (original) Ecliptica album came on my playlist today and reminded me how good they were. Ecliptica was a ridiculously epic debut album. Blank File and Full Moon are still stone cold classics. Love how both just keep the intensity going from first to last. I was okay with them experimenting, but it sucked that they pretty much lost all their intensity, and by the time they decided they wanted to get it back it was too late. They didn't have that youthful energy anymore and it came off as contrived. You could tell they'd lost that sense of youthful exuberence when they botched the Ecliptica rerecording, almost as badly as Clayman 2020, but at least IF only rerecorded and ruined a handful of songs, not the entire fucking album.
But yeah, Ecliptica, masterpiece. Blank File, My Land, Replica, Kingdom for a Heart, Full Moon, Letter to Dana, Unopened... none of those ever get old to me. Kakko's vocals are far from refined, but he sounds earnest and I like that his style allows him the flexibility to inject emotional range into the words he's singing.