I should have included this in my weapon damage by hit die post, but I didn’t think of it then. Check out this simple table of correspondences:
- Fighter hit die: d8
Iconic weapon: long sword (d8 damage)
- Cleric hit die: d6
Iconic weapon: mace (d6 damage)
- Magic-user hit die: d4
Iconic weapon: dagger (d4 damage)
That is, characters playing to type in B/X D&D naturally do hit die damage. The relationship breaks down slightly when ranged weapons are considered. Long bows inflict d8 damage and slings inflict d4 damage, fitting the pattern, but what ranged weapons do clerics use? If it’s a crossbow with a wooden stake, we are in business. In any case, the point here is not that this is an iron-clad rule, merely that it is a tendency.
The thief/rogue actually fits this pattern relatively well too, with dagger/short sword, and d4/d6, respectively. This also reflects the change from the thief (sneaky, bad at combat) to the rogue (stealthy, striker).
The main benefit of damage by hit die is to reduce a rather complicated table reference (the weapon damage chart) to an easily memorable rule. This is similar to what Talysman is trying to do (*) with his Liber Zero clone project. Note that this is not a core mechanic, which may have only one kind of resolution mechanism, but may also have a huge number of very specific rules for modifying the target number based on circumstances. Easily memorable elements may use several different resolution mechanisms, but they must not rely on a large corpus of external rules to function.
(*) – In his own words:
one of my personal goals with Liber Zero (quickly becoming the central goal of LZ) is to strip the game down to easily-memorizable elements so that the game can be played without reference to books
See here for more details.