The community seems to be split over the radar. 2/3 seem to want to increase radar range and the other 1/3 would prefer that players use their eyes.
There is not a shadow of doubt that the radar has a huge impact on the way the game plays. With proper radar distance, actual battles happen where people test their wits against opponents and the most skilled player wins. With no radar, you must rely on your teammates more and the game becomes a little more CoD like because it is more of a who-sees-who first since the radar does not alert players to each others presences. Proper coordination, movement, and awareness is what will win.
Personally, I have enjoyed radar for the last 5 Halo games. I like engaging my enemy and not always getting shot in the back and not having time to retaliate. With faster movement speeds along with the sprint beatdown charge, radar at 18 meters is useless. Buff to 30 meters and 2/3 of us will be happy. Add in a hardcore mode with no radar and the other 1/3 will be happy.
Both sides of the community are happy. Problem solved.