It is a very painful limit for us and a support request generator.
Excel interop functionality we implement for our smaller clients can easily fail for our larger clients because of their workbook sizes.
Therefore, we need make our context.sync() invocations more granular. However, because cell contents/formatting can differ between different clients, we can easily become overly cautious and ruin the performance with too many syncs.
I don't think batching of synchronizations should be imposed on developers.
We would like Microsoft to abstract that limit away from us and batch it under the hood of Office.js.
My rationale is that the framework is in a much better position to know how many changes have been accumulated, and whether or not these changes should be batched into several addin <-> host calls.