The drive is fine in nice weather but road condition can be treacherous after snowstorms and it can lead to road closures (I-70, US40), making flying more attractive.
DL couldn't make HDN work because it ran daily flights to ATL only, which meant longer travel time for most of the country, whereas UA has multiple flights per day to its DEN hub.
Huh? Delta still flies a 757 daily on ATL-HDN-ATL. One leaves in a couple hours. They’re also doing MSP-HDN this winter. These went away during covid, then came back.