I can tell you why, from a design standpoint, 1st Edition AD&D STR attack and damage bonuses are lower than other bonuses at a given score value.
(1) You want ability scores to all be about the same usefulness. Yes it’s true that for some characters WIS is not very important, but that’s also true of STR for some characters. The existence of an ability score’s derived modifiers should signal to the DM what to include in the game. If WIS seems like a dump stat because all it gives most people is a save bonus against mind-affecting magic, perhaps the DM should include a little more mind-affecting enemies (note that many mind-affecting spells seem to be save-or-lose such as Hold Person and Charm Person and appear on low-level spell lists, so when you do encounter them a saving throw is highly impactful).
(2) STR does a lot of things. Attack bonus, damage bonus (both in melee with narrow exceptions), carrying capacity, Open Doors, Bend Bars / Lift Gates. Because it does so many important things, if it gave all those things the full bonus (+1 at 15, +2 at 16, etc) it would be a very powerful ability score. Note too that while Monks in 1e PHB don’t benefit from the STR score, that doesn’t mean they use some other stat in exchange.
That 3e stuff doesn’t exist in 1e. There’s no Finesse weapon using DEX so you can follow a DEX-monkey build with 5 dump stats. If you’re physically weak, that makes you suffer in melee combat, as is true in reality.
Some DMs might not recognize that STR does multiple important things, if they improperly de-emphasize encumbrance, Open Doors, and BB/LG. Thief skills are useful largely to overcome specific adventuring challenges (locked doors, traps, elevation change) and establish surprise. Fighter-types, especially those with exceptional STR, are good at overcoming stuck and locked doors and chests. Picking vs. bashing are two valuable approaches to some of the same challenges, with their own benefits and drawbacks. Picking takes longer but is quiet and failure doesn’t alert the enemy on the other side, and can’t be used to lift a portcullis or dislodge a stuck door for example. Bashing is an immediate blow-through that can use multiple people at once, but entering like that uses those people’s actions on that surprise segment so they can’t immediately take advantage of possible enemy surprise – while bashing with just 1 person reduces success chance and a failed bash alerts enemies inside before you can try entry again. The point is, if the DM isn’t making a large minority of dungeon doors “stuck” or including a few bars to bend or portcullises to lift, they’re not including enough of that challenge type and it’s unsurprising that players ignore that column of the STR chart.
Encumbrance is the old bugbear of D&D paperwork, and there are tons of creative ways to make it easier and integrate it better into other gameplay. Note that Gygax’s game design telegraphs to players that treasure was the objective of the game by setting the XP tables to assume the award of 1 XP per GP, and carrying capacity to “how many coins can you carry out”. If the DM ignores encumbrance by handwaving it, or giving everyone Bags of Holding AND ignoring it, it detrimentally impacts so many other aspects of the game that it shifts the entire thing. It’s as impactful as playing Monopoly without money. It’s also common for a DM to short-circuit the encumbrance puzzle by making treasure very light. By design, it’s not until mid-levels (when PCs’ carrying capacities are also higher) when treasure starts showing up that’s very value-dense such as gems, jewelry, and magic items. At low levels it’s piles of gold coins, heavy silver ewers, furs, nonmagical arms and equipment, etc. The DM must also include environmental difficulties that make transporting the heavy loot back to civilization a compelling puzzle, such as vertical climbs, tight squeezes, gaps like pits and crevasses, resetting traps, monster activity, and wilderness treks with terrain and weather – and the possibility of getting lost or unwisely sidetracked at any point. Having great carrying capacity is thus highly valuable to an adventuring party, not only because far more equipment can be brought in per trip, but because far more treasure can be hauled out.
The second, separate issue with rationalizing STR attack and damage bonuses to the same progression as other ability scores, is that an attack bonus increases average damage output. If you have +1 to hit, your average damage during that campaign will be about 5% higher. A Longsword +2 gives average damage 6.5, but with 3e’s 18 STR modifier of +4 to hit and damage from STR that would become 12.6 (+4 for the damage bonus, +20% for the additional hit chance). If we use the 1e STR modifier at 18 of +1 to hit and +2 damage, it’s only 8.925. The average damage bonus gained from an attack bonus applies to all other damage modifiers, too, so inflation in damage is exacerbated by inflation of attack value. The missile attack bonus from DEX is higher than the melee attack bonus from STR, and also doesn’t include a missile damage bonus. This is not an oversight. Note too how DEX in 1e offers multiple extremely valuable benefits, so its bonus progression is slower than INT, WIS, or CON.
As for CHA, DMs should really use the reaction adjustment and loyalty rules, and encourage hireling and henchmen use by portraying them in the campaign and including their costs in the player equipment handout alongside rope and horses. But you’ll notice that when comparing the CHA modifiers to other ability scores’ by converting to d20 odds, the CHA bonuses are very high, with an 18 CHA giving a +8 in 20 to reaction adjustment and +7 in 20 to loyalty base. CHA is an incredibly powerful ability score, if the DM is using the tools laid out for them!
To compare 1e AD&D with Basic’s 1991 Rules Cyclopedia, which uses the 3e-style combined ability score modifiers (albeit with a slightly slower progression to +3 at 18 and a MUCH slower progression thereafter up to +20 at 100 in the Immortals set). Combine that with a slower THAC0 progression, and different rate of attack by Fighter-types. It’s difficult for me since I’m no Basic expert, but it feels like removing EX-STR and nudging everything else regarding melee combat around, was a pretty good design choice.
1d30 