Everywhere I keep finding "to achieve low latency" or "latency is of concern", do this!

So, I don't really get what are the other concerns other than latency. I mean who doesn't want low latency? Or do they?

Of course, packet loss could be one concern. In production systems where users work with data on a remote network (Eg: NFS), packet loss is not accepted. But doesn't TCP protocol resend a packet if an in time acknowledgement not received. If not, I guess we shouldn't worry about packet loss which might occur not much frequently, unless the architecture allows it to be.

So, are there any other concerns?

I am not from networking background. So, I am wishing that the explanation is as elaborate as possible.

Thanks!