The reason molars are the only teeth that can be hidden is to represent them as unerupted and allow the odontogram to more accurately represent what is actually visible when you look in the mouth. The other teeth don't have this option because they have primary teeth that precede them. If any of the other permanent teeth are unerupted rather than hiding them you would either indicate that a primary tooth holds that spot, or that the primary tooth that was holding that spot has been removed/extracted. The condition "Missing" is for teeth that are congenitally missing or never formed, although it is often incorrectly used for teeth that have been extracted.
The reason molars are the only teeth that can be hidden is to represent them as unerupted and allow the odontogram to more accurately represent what is actually visible when you look in the mouth. The other teeth don't have this option because they have primary teeth that precede them. If any of the other permanent teeth are unerupted rather than hiding them you would either indicate that a primary tooth holds that spot, or that the primary tooth that was holding that spot has been removed/extracted. The condition "Missing" is for teeth that are congenitally missing or never formed, although it is often incorrectly used for teeth that have been extracted.