Hickory: That's precisely my point. BG original has no 1080p. It is designed for 640x480. I have both versions and if you compare them at the same zoom/resolution the evidence is plain to see. Convince yourself of the lie if you must, but the evidence doesn't lie.
Does someone even play BG1 in native resolution these days? Almost everyone uses widescreen mod when playing the original version. And the fact is it's nearly unplayable in 1080p due to tiny assets. You can change the resolution of EE, if you really want to. This will solve the graphics downgrade because you won't have to use zoom.
Hickory: Remember the assets in this game, regardless of version, are fixed. The original assets were lost so the 'enhanced' versions are second-hand copies made by ex-modders. The enhanced 'zoom' gimmick is nothing more than screen resolution manipulation.
From what I've heard only some assets were remade. This includes characters and their animations, UI and perhaps some other things. I don't think Beamdog has changed any of the environment assets.