I suppose you could also repair the computer if the full logic board hasn't died, but that may not be worth it if the laptop was purchased a while ago, especially given how unrepairable these devices are. And depending on how Apple decides to go about the repair, they may end up not retaining your anyway, even if they could have.
This does not change the fact that removable storage (or even storage that's accessible post board-failure) provides an additional margin of risk mitigation against hardware failure. AND a convenient way of making bootable backups you can swap in the event of storage failure rather than taking the entire machine out. AND upgradability.
What's the advantage of soldering the SSD to the board?
(And personally, I've experienced boot failure hardware issues on two laptops, theft zero times.)
How much additional margin? If you have backups, you're covered against both failure modes; the only marginal benefit would be to recover the x hours of data since your last backup.
I would wager that for 90% of people, that would be all of the data since initial power on.
Or just spend years sitting unused in a box in an attic somewhere!