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.