We have set up actions that send us information when we want to be informed, we have remote commands that can even restart services as needed and do many other things. So why visualize anything?
While for most this question will seem silly because we know quite well what data we would like to visualize, not all functionality will be obvious.
Of course, it can be easier to assess the problem when looking at graphs, as this allows us to easily spot the time when a problem started, correlate various parameters easily, and spot recurring anomalies. Things such as graphs can also be used as a simple representation to answer questions such as so what does that Zabbix system do?" That does come in handy when trying to show results and benefits to non-technical management.
Another useful area is displaying data on a large screen. That usually is a high-level overview of the system state, and is placed in the system operators' or helpdesk location. Imagine a large plasma TV, showing...