All electrical boxes must have covers.
All Romex wiring should be behind sheetrock. This application could have been completed with BX cable or conduit. You should never see an wire nut, they should always be in junction boxes with proper covers. If these connections were to fail, there is nothing to contain the potential sparks and could result in a fire. This was an example of handyman wiring and made us conclude that it was not performed by an electrician and not inspected by a municipal inspector. We noted this as unprofessional wiring.