For me it's not so much where the "stupid gap" is in the screen as that it allows you to see some of the area real estate along the edges. This provides an illusion of access to the full screen for viewing, as well as making the area fit the golden rectangle ratio of the typical screen display. When you are moving a party in some direction, the edge of the screen is normally where you will be looking to see upcoming risk factors. Having that blocked off by a solid bar feels hindering.
Yeah, well I can understand that it may feel limitating and kind of artificial. But in my opinion since this is a game that uses RTwP and a fixed camera, it is not really needed. You'll be pausing the game often and its not going to be that much of an issue.
I'm not really sure if I prefer BG2 or IWD2 style more, modification between those two would probably be the best.