[tromp]

Yes, losing access to the underlying data is a big downside.

I think the ideal blockchain should offer constant time historical verification in addition to rather than as replacement of verifying the tx history. That also makes it robust against possible bugs in the design and implementation of the rather complex IVC technology.

Even if IVC is the only way to verify the full history, then it could still be limited to older history, e.g. up to a week or month ago. That would give you some time to investigate recent hiccups.