Traffic and roads
The south end of Salt Lake Valley is notorious for traffic backups that begin in Salt Lake County and spill into Utah County to the south, daily for both the morning and evening commutes, with no established secondary routes that can handle massive event traffic. Salt Lake City, conversely, handles not only Jazz traffic but large conventions and daily commuters coming in and out of the busy city center.
The Bottom Line
It doesn't make a lot of sense to build a new arena in Draper, Utah. Ryan Smith, the Utah Jazz majority owner, might be seeing dollar signs in pushing the Jazz towards a population that is growing rapidly and could draw more casual fans to the team.
But the risk of alienating a core portion of the fanbase, strong corporate sponsors in Salt Lake City, and centralizing the team in a suburban environment might not work well long term for fans, players or the ownership.