A nice increase to weight allowance and 7x greater chance to bend bars/lift gates for strength. Greatly increased system shock and resurrection survival rates for con. You left out a significant intelligence difference. The min/max known spells for wizards. Dexterity had some significant penalties to thief skills from 9-12. Charisma increased henchman and at 14 increased loyalty and reaction rolls.
So Wisdom, Strength, Intelligence, Constitution, Dexterity, and Charisma all had significant differences from 9-14. Woah! That's all of them, leaving 0 where there was "...pretty much no difference between a 9 and 14.".
While I agree that there were differences, most of them only applied to you if you were a class that cared about the ability score. That is you really only cared about chance of clerical spell failure if you were a Cleric, or the maximum knows spells if you were a Wizard, or changes in the thief abilities if you were a thief. For most classes though, if you had 16 in your prime requisite, everything else was basically gravy. And having an 18 was a huge advantage over a 16, but really only if it was your prime requisite. A cleric might love an 18 Str, but it would be largely wasted on a cleric, as the bonuses from 18/XX strength were massive compared to the difference between a 16 and an 18. Unless you were a fighter, 18 Con was about as good as a 16 Con.
There are really a short list of 'playable' builds for 1e once you become familiar with it:
Qualifies for Paladin. Lucky you. Play a Paladin.
Has at least a 17 strength and at least a 17 constitution, and no stat of 5 or less. Play a human, dwarf, or half-orc fighter. This is a power gamer's dream build. You have one of the most powerful characters you can get, and post Unearthed Arcana such a character can be game breaking.
Has at least two 16s not in Charisma or Constitution, and no stat of 5 or less. You have a lot of flexibility, and really can make almost anything work. Plan a human dual class build, a cavalier, or play a straight classed human with extra advantages, or play a multi-class humanoid where one of the classes is thief or assassin.
Has at least one 16+ not in Charisma or Constitution, and no stat of 5 or less in a conflicting attribute. Play a straight-class with the appropriate Prime Requisite.
Has at least a 16+ on Constitution and strength is 9 or higher. Play a Dwarf fighter.
Qualifies for Bard. Begin a Bard build.
Has at least two 15+ not in Charisma or Constitution. Plan a dual-class human character.
Qualifies for Ranger. Play a Ranger.
None of the above. Roll up a new character, or commit suicide if you can't.
Two or more fives or less. You can't make a character. Roll up a new character.
While there is some small granularity between 9-14, unless you qualify for Ranger, there is no point in playing that character even with above average rolls, because the gap between a 17 and an 18 and an 18 and higher than an 18 is just massive. A fighter with 18+ strength, or a dwarf fighter with 19 Con, or a Wizard with 18 intelligence is just massively more potent than anything with no scores above 14, and even multiple 15's is barely playable unless you qualify for a 'prestige' class.