Not everyone knows what latency/ping is, no, you are right.
The icon used is not the worst they could do but numbers would still be better. Underlying the symbols used, there are numbers. These can give a far better idea of response times, provide an indication of where you are likely to be gaming and are thus a good for diagnostics if things are going wrong.
Ever since BF1942, DICE have failed to provide a decent game browser with reliable ping info. BF2's latency info is totally unreliable despite giving you figures. It's way out.
If a game is reporting less than 30ms, you know you should expect a nice smooth experience and that it's highly likely the hosting server is UK based. 40 - 60ms and you might be in France, Germany etc. Around 60ms and you're in northern Scandinavia maybe. Granted, latency isn't everything in terms of network reliability but it's a pretty useful indication of where to avoid playing.
So, yes the little wifi signal thing ought to show a player where they are more likely to obtain a good experience (full signal strength) but what info is behind that? What are the characteristics? I think I recall back in BF1942, you could at any time press the tab button to bring up the score and see your own ping, dynamically changing as well as others. That's useful info and not exactly beyond most players of this kind of game's experience and capability to grasp what it's telling them. Now, the console crowd... Might be a different story though there are likely plenty like mrnelster who might find a bit more info useful.