When in unfamiliar territory and your going like the clappers from hell and all of a sudden a bend appears in front of you then you've got problems if you've failed to follow the map, by a quick glance down at the Garmin map display I can see what is coming up fast upon me. Likewise I can see by a downloaded profile if I am at the top of a hill or is it just a false brow. Its simple, same as I use my car GPS, I can see what's coming up ahead and out of sight. Its technology to be used for such purposes. Do rally drivers, co-drivers not give out info of what is coming up in a rally, or does he just sit there like a dummy whilst the driver just drives with no situational awarness of what is coming up ahead.
If it was a case of just looking ahead and never failing to make a bend because you will always see it, explain why we see so many holes in hedges and fences etc where others have made the same mistake
And as for telling me about potholes etc coming up, yes, I can input that information of known hazards on my route, like I do with the start of climbs and feed stations etc if I am that concerned and I will get a warning when I approach it.
Why do you think the Garmin "Edge" is called so, I'll give you a clue the answers in the name. And when your out racing and fast group rides, any "Edge" you can get, helps.