EV batteries should have been designed so individual small modules could be replaced at reasonable cost as they fail, rather than the entire battery all at once.
The design was likely necessary in order to cool the battery packs. The liquid filled cooling strips are interwoven between the batteries. I've seen some videos that battery designers are trying to make them more modular with a different cooling method.
“EV batteries should have been designed so individual small modules could be replaced at reasonable cost as they fail, rather than the entire battery all at once.”
Hear! hear!
Many damaged EV batteries can be repaired, because most are made from hundreds or thousands of small cells, and sometimes when just a few have gone bad they can be located and replaced. But doing this type of work can be dangerous and takes specialized equipment. And as you have pointed out, they are not designed for easy repair.
The problem is that if the cells in the battery are allowed to go below a certain voltage they are irreparably damaged and the type of negligence that causes this type of failure likely will cause many cells to be damaged... not just a few.
The short Mercedes AA Class video explains how Mercedes does just that. It's worth watching.