It's a nod to the tabletop systems and consistent with the rest of the game. Did you bring enough supplies to prepare for your journey?
I actually appreciated it, personally. I thought it was a nice touch on an aspect that too many games just hand wave or gloss over. Outside of something like Ultima with the food number or Realms of Arkania with all sorts of preparation items to manage, I can't think of many games that actually deal with travel and its necessities.
Supplies are irrelevant, you can just hunt and carrying that many rations is silly (especially when you guys are telling me to stay "light"). Timer mostly irrelevant for me so far, and you could just increase the travel time anyway to make it have the same impact.
Again, the flawed thing is the gameplay mechanic of stopping and resting during map travel killing the pacing for no real purpose. You want to go from map marker A to map marker B and you have to stop and do the tedious resting process that has no deeper gameplay functionality a few more hours on the clock couldn't handle. It's just clicking two buttons and waiting to move on the same route you were already going down, delaying you getting to the real gameplay. Your second sentence seems to be more the motivation, but I've never been one to desire pointless realism nods in video games. If you can't just assume they're resting during the normal travel time you're probably on the spectrum.