Provide a visual impression
For good interior design, creativity is essential and the product should support creating good interior design by providing an optimal visual impression of the displayed environment. Users mostly want to decorate a room (use it for interior design) and for an optimal decision on how to decorate and what products to buy it is essential for users to have a good visual impression of how the AR room would look like in real life. If there would be a bigger difference, the real room might look bad even though the AR arrangement looked fine and users may become frustrated. The tool would not fulfill its purpose.