Those batteries fail and leak all over the board around them, destroying traces and components. These aren't your typical lithium coin cell batteries that are very good at not leaking.
When a leak happens, even if you can fix/replace the components mounted to the boards, when you've got multi-layer boards it gets hard to figure out how repair the damage that happened to the internal traces and such.
If possible, replacing those batteries with something less likely to juice all over is what you want to do. And since you don't really know when it will start to leak, getting those old batteries out NOW is the safest option.
When a leak happens, even if you can fix/replace the components mounted to the boards, when you've got multi-layer boards it gets hard to figure out how repair the damage that happened to the internal traces and such.
If possible, replacing those batteries with something less likely to juice all over is what you want to do. And since you don't really know when it will start to leak, getting those old batteries out NOW is the safest option.