I understand the concept of the graphics being a supplement to the text in NVL mode - sort of just hinting at a scene and be complemented by a more detailed account of the situation in the text - and I think it works quite well when the graphics are simple or simplified, because the text can fill in the detail.
However, when graphics reach a certain level of detail and color variety (which they definitely have done in EH), and you want sprites and not words to convey a lot of the emotions, the NVL mode layout starts to waste that detail with the letters that break the lines (especially bad for registering facial expressions), and diminish the impact of nice colors and lighting by washing them out when looked at through its semi transparent overlay.
So unless there is an artistic message you need to convey, I think that as a general rule when you have nice or detailed pictures, you should use a display layout which highlights them - a good way of determining whether this is the case is whether you present screenshots without the NVL mode overlay, or with it. If your webpage has pictures where the NVL layout is hidden, then you probably like the pictures and want to show them - consequently you should try to show that picture to the player when he is playing, so he can see the information and feel the atmosphere it's giving him.