I don't think you need to be that worried about "tightening control to the likes of Apple". Given that they encourage people build their own cases for the motherboards, design and 3d print custom expansion cards, I won't be surprised if some 3rd party designs a whole new motherboard to fit in their chassis since the size is supposed to be standard. Iirc, Louis Rossman did do a video on them in the past that confirmed Framework would be willing to work with repair shops to provide them the schematics that they are able to provide to aid in repairs.
On the other topic, I agree that most people won't be needing to swap out parts that often. But that's also the beauty of modularity though. You buy the parts that you actually need and nothing else. Framework can sell the exact same chassis that still fills the need for different people who have different needs for ports. And since they're supposed to reuse the same chassis down the line, you are almost guaranteed to have parts still be available multiple generations after, unlike modern laptops where parts would be much harder to find after a couple of hardware refreshes.
Framework is still a niche product, thus they will definitely still be much more expensive than regular laptops due to scale and whatnot. Most people would be better off buying those tbh. But if you care about upgradability or repairability multiple years after purchase, I think they're still worth considering.