when viewing a graph, values or 500 latest values for an item, previous zabbix versions had the hostname as a link back to the latest data page for that host.

in 3.0, the host name is still there - but it's not a link anymore.

the link was very useful when an alert email had a link to the item graph or values. it also acted as a way back to the list of items, somewhat preventing the "dead end" navigation impression.