I see. We have different connotations of the word, then. For me, a museum is just a place where objects of historical interest are stored.

When I talked about humans being "preserved mostly in history books and museums" - I was intending to conjour up an institution somewhat like the Jurassic park theme park. Or perhaps - looking further out - something like The Matrix. Not quite like the museum of natural history as it is today - but more like what it will turn into.

Regarding the utility of existence in a museum - it may be quite a bit better than not existing at all.

Regarding the reason for keeping objects of historical around - that is for much the same reason as we do today - to learn from them, and to preserve them for future generations to study. They may have better tools for analysing things with in the future. If the objects of study are destroyed, future tools will not be able to access them.