There are situations which require to have a clone of a host including its history/trend data. This could be the preparation of substantial changes which carry the risk of loosing that data.
To make it more concrete: I have to change a host's data collection method from SNMP to HTTP. Especially in combination with LLD there is the risk that the discovered items get deleted and recreated. So all their history/trend data would be lost.

So I would really appreciate having the option to clone a host including its history/trend data.
An alternative or maybe even better solution would be extending the host export/import function to also include that data. With this one could even copy a host between two different Zabbix instances.