What about the data would require an expert to reconstruct? They have the simulated flight path. It's very similar to the final flight path of the real plane.
From the report it was recovered from backup files at the system level, it wasn't as simple as a save game file or whatever. It's possible there's more data there or that what's there has different interpretations - we can only speculate at this point based on the very limited information that's been released.
Probably because it wasn't just a simple 'replay' file.