A post on the Shugashack has word from Zoid explaining why a packet loss indicator was not included in the final Quake III Arena point release (story), which was expected since a Graeme Devine .plan update mentioned "Packetloss on the scoreboard" as one of the bugs they were "looking at." Zoid's explanation points out the impact of packet loss is harder to gauge in Q3A (and lesser) than it was in QuakeWorld, and also notes that packet loss is also reflected to some extent in your ping.