This little nite stand is actually used to house the furnace
. You will notice only the top of the cabinet has a small drawer in it and the vent below.
If you were to widen the bed, you would have to house the furnace
as part of the reconstruction, but it is doable. I would say the only issue might be increased difficulty in making up the bed as you now have 3 sides to tuck the sheets into.
The other consideration might be ( and likely the reason to not do it) is the walkway at the bottom of the bed is now reduced significantly to get to the closet to the point of having to hop over the mattress each time.
Another consideration, is the resale value once completed with a major mod like this might not be desirable to many folks as compared to the stock bed design.
Otherwise a doable mod if the benefits outweigh the negatives.
Hope this helps!