and here are the cities ordered by percentage growth from 2000 to 2010
Couple things. Indeed, SLC is sparsely populated compared to the surrounding suburbs and it hasn't been growing much over the last ~13 years, especially compared to the rest of the county. In fact, except for Sandy, SLC has been growing more slowly (in percentage terms) compared to every other city in the valley (and Sandy's population density is much higher than Salt Lake's, so one can't say SLC is full). With population along the Wasatch Front projected to grow by 1.4 million over the next 30 years, to remain relevant, Salt Lake City will have to remove its barriers to population growth. This would also go a long way to help mitigate our air quality issues, as current SLC policy appears to be pushing people out to suburbia in giant numbers.
Postscript: To be entirely fair, these numbers leave off the last 2-3 years (which we'll look at soon), but it would be quite difficult to make any solid conclusions from the sparse population data available since the 2010 census.