FYI, I don't work for Skywest or live in Utah. However, my home airport is served by flights to airline hubs at SLC, DEN, LAS, PDX, SEA, and MSP, listed in my order of preference.
I also fly cargo into SLC frequently, along with other carriers who view SLC's location and airport as ideal for the hub in the area.
Also, don't forget that there are other competitiors in the western US. Having western hubs in SEA and LAX would provide a lot of domestic overlap with Alaska/Horizon. Additionaly, many customers would be drawn away from Delta to other hubs such as DEN, LAS, and PHX that can provide lower costs, faster times, and yes, even international connections.