You could do that, if you're actively checking ping roundtrip times. It was in a local network and generally, the connection was working, so we didn't think the ping or roundtrip times would be relevant.

Our software was just routinely logging ping+RTT and when scrolling through the logs, we noticed more or less by chance that the RTT is 300 ms, which is absurdly high for that context.

And well, this is just one example. If you're doing time-sensitive stuff, it's useful to know the timings of what you're dealing with. It's not usually essential, and you especially don't need to know it for every possible context. But it can make your life easier.