To manage hosts and templates it was very very useful in pre 4.0 versions:
Host Groups - in the editior i could add/remove hosts to the group, screenshot hostgroups.png
Templates - in the editor i could add/remove groups and hosts, screenshot templates.png

This functions in the frontend are very important because assigning of hosts/groups/templates is very easy, fast and save. I'm working with many hosts/groups and templates and for me it is a no go for upgrading to version 4.x for production.

Unfortunately you closed the issue ZBXNEXT-4725 even thoug not fixing it.