It would be great if Zabbix could support longer hostnames thant 64 chars, which is especially relevant in cloud based environments, where there's no direct control over hostnames and together with the addition of domain names they can be a lot longer than 64 chars.
Although literrally Zabbix is conformant to the RFC we could use longer names. Relevant fragment:

Host software MUST handle host names of up to 63 characters and SHOULD handle host names of up to 255 characters.