One of the main reasons for the opening is hygiene. Removing the front section reduces the amount of contact users have with the seat, particularly around an area where additional space can be useful. The design can also make the toilet easier to use comfortably for different people.
The open-front shape may also make cleaning and maintaining the seat easier, which is especially valuable in busy public restrooms. Because these facilities serve many people every day, simple features that improve sanitation and make maintenance more convenient can have practical benefits.
What initially appears to be an odd or incomplete toilet seat is therefore a deliberate design choice. It’s a small example of how everyday objects can contain practical features that most people rarely notice or question until something about their appearance catches their attention.
