IF a real-time racaster was coded somehow, i'm doubting it would use all 32 columns in the playfield. Most likely 16 columns, using 2 columns rows per scanline. it wold be crappy looking, but if the maps made for it have wide hallways you won't notice to much.
The only problems I see with the way roland p's game(and battelzone for the 2600) renders is that it makes map creation way more difficult(if not impossible) and like mentioned before, It's not a raycaster.
It's not a bad idea. It does get rid of the need to make the walls different colors(because they're all outlined), so it wold save me from having to turn my 70 pound tv sideways every time I want to test it. However if you were talking about the sprites then it is completely unnecessary, unless you want them to match the theme.