Good question. My guess would be that they are hoping to fill it with believers, because as far as I know they have not allowed non-Mormons inside since shortly after it was opened. My BF got a tour before they closed it to the public, he said it was unbelievably beautiful inside. It's quite a lot bigger than the pic indicates, only 3 of the 6 spires are visible from that angle.
This whole area is known for building huge structures that remain virtually empty. They knocked down one of the last few houses remaining in the downtown region of my town to put in more luxury condos despite the fact that the numerous apt/condo high-rises already here go begging for occupants. My fave shortcut was next to that house, dammit. Office buildings are the same, they have entire floors vacant, but they keep putting up more buildings.