In a world where teleportation magic doesn’t exist, the opportunity to travel a few days journey in moments is beyond value. With only a simple toll, you can be practically on the doorstep of Nizul-tibi before you know it.
When was the last time a character caught a cold or flu? Real people get them every now and again even with solid heating and dry interiors. Your characters are out in the cold and wet, and even inside is not always dry and warm. Imagine having to stop your dungeon crawl, sitting in a tight defensive position, while you all are feverish.