It pretty much comes down to three things, all driven by their system's modularity:

1. Repairability and upgradeability. You get officially supported spare parts for everything and they intend to keep selling compatible parts for the foreseeable future. Due to them internally standardizing their form factors, all parts are intended to be upgradable, even the logic board.
2. Swappable ports. Being able to reconfigure every port into whatever you need reduces the need for docks and adapters. Since the specs are open, third parties can make their own ports or offer compatible slots in their devices.
3. Reuse of components. At least some components like the logic boards are fully intended to be used outside their laptops, e.g. after an upgrade. I'm not sure if they offer detailed enough specs on stuff like the fingerprint sensor to use that for your own projects.

Whether this is worth it is up to you. Anecdotally, I have to replace my current laptop because the keyboard is dying. The rest is still fine, it's just the keyboard. In hindsight, paying more upfront and being able to just order a new keyboard for fifty bucks would've saved me some money.