Another point to illustrate the small size:
Here is the SLC Terminal plaza compared to the SeaTac Terminal Plaza, built in 2003 when the airport was hovering around 26 million passengers a year, nearly the same amount that Salt Lake City is currently at. Their plaza is constantly overcrowded, crammed, and too small for their current passenger use and spatial need. This is purely observation, but every time I have flown through the airport there is little to no chance of finding a seat in the plaza. As such, their current expansions and remodels of various concourses have emphasized increased public gathering, eating, and sitting space in their designs to accommodate the lack thereof.
The following pictures illustrate how SLC's plaza is less than half the size, as Seattle's is over 200 feet wider (more the twice as wide). It is also is roughly half the ceiling height, as SLC's is 56' and Seattle's is 96'.
Again, at the time of construction both plazas were/will be handling the same amount of passengers.