It appears that any rationale that may be given for why tea and coffee are forbidden but other drinks are not—besides that God commanded it to be that way—cannot be sustained logically:

  • Caffeinated sodas are OK, but coffee and tea are forbidden because D&C 89 forbids “hot drinks.” It’s not about caffeine.
  • Hot chocolate is OK, despite being hot, because “hot drinks” really means brewed drinks.
  • Iced tea and iced coffee are forbidden, despite being cold, because they are brewed.
  • But herbal teas, hot or iced, are OK, despite being brewed, because there is no caffeine.

With modification from here.