Why was architectural engineering needed to study interior design?

Architectural engineering is light on building design when compared to architecture. The rest of the training is in the building systems. Structural engineering is about on pare with architecture, but electrical, mechanical and plumbing engineering training goes farther.

Now, why would you need to know this? (Keep in mind that interior designers should be able to change walls and finishes and are not just interior decorators.) When changing/ modifying interior spaces you need to be able to identify which building elements you can change and which you can’t. Also, you need to know enough about them so you can accommodate them in your design.

No one is asking you to design a structural wall or sewer pipe, but they do expect you to be able to identify them (and know if you can change them).