As I was reading through the monster creation rules, a thought occured to me...
The only ability score that is used at all for any level of creation is Strength (it adds to melee damage). Beyond that, everything is based on the CR of monster being created.
So why bother?
Pretty sure the ability scores are relevant to things like initiative and skills (especially but not only Perception).
How many skills are relevant to the monster probably depends on the concept and the situation.
I find a good rule of thumb for these "why bother with rules for such-and-such" topics is to remember that Starfinder is designed to have rules applicable to a huge number of different situations depending on what a given table is playing. Why bother with environmental rules? Because some people want to play adventures that use them. Why bother with character abilities that aren't relevant to a 100-by-100 foot combat grid? Because there are games that use more settings than that. Why bother with whether your alien worm monster has a high Charisma? Because maybe you'll want it to be able to make Intimidate rolls without having to give it a special power for that. Etc.
I understand that the way it's written lets a wide variety of play, but for your specific example (skills), the ability score only matters if it's not one of the monsters Master/Good skills, which have preordained values which ability scores do not effect...
Maybe it's just strange to me that Strength DOES affect actual crunchy combat stats while the rest of the ability scores don't (Dex doesn't affect AC, Con doesn't affect health, and so on).
Yes you're right, it does affect Initiative, I'll give you that.
To answer your question: some class feature, like Inspiring Boost, would still be modified by an ability score if they were given to an NPC. Even if they have no such abilities, their scores can be used for descriptive purpose (what does a Str +3, Dex -1, Cha +2 person look like?), or to roll for skills they aren't trained in (perception is not a good or master skill, so he gets +2 to his roll from Wisdom instead)
Better question, though: If we're being honest, did the other ability scores ever matter before?
The bulk of monsters/NPCs never stick around longer than a single encounter (whether it's combat, shopping, or what have you). Very rarely to they have much opportunity to do anything other than attack or use the skills you intend them to use (like guards, that will probably use perception and sense motive, but not life science).
Why bother adding them to things, or calculating skill bonuses the old fashioned way? No one will ever see or appreciate that math except for you, and if the attack bonuses, hp, and the like of enemies averages out to a specific number anyway, we might as well use that number. There isn't much difference between 100hp and 120hp when an attack can deal anywhere between 20 and 30 damage depending on the roll.
I'm sure you can probably ignore the finer details for any monster you're just generating as a one-off and just focus on the things you specifically need. Other things like Attributes and Skills are there to provide a big picture of things a monster could be used for.
I tend to just use the estimable Mike Cadzow's Monster Builder which TBH makes it easy enough not to trouble thinking about.
So far, I've created over a half dozen new races, and none of them has stats catering to Strength - not one.
I've got some new monsters as well, and strength is their forte either.
One called Chaldron has multiple life stages. Basically a crab is kind of an "alien" facehugger that attacks like a big insect, and they hunt in packs. If someone is rendered helpless, then a Chaldron minder makes them into kind of telepathically controlled slave. And used as animated dead (though the person controlled isn't dead). The adult Chaldron is the being with mind-control abilities. The facehugger crabs leave an egg inside the controlled being and eventually explodes creating a new Chaldron minder adult and killing he host.
Their power is the pack in crab form, and mind-control by the adults - strength has nothing to do with either form.
Are all Pathfinder monsters strength based? If not why not? Same as Starfinder, so I don't get the premise of this thread at all.
I think the intent of the question was that Strength and Dex are, for 90% of NPCs, the obly stats added to anything (melee damage and initiative), as all other statistics are simply flat numbers.