The problem is that when you manually spot stuff, BF2 is really finicky, and you'll easily get a target spotted 100 meters too close or too far, etc. Like if you try to spot someone on the top of a hill but then it spots them way behind the hill or you try to spot someone through a forest but your aim hits a tree or the little hill directly in front of your face, etc.
So if you switch to manual spotting, you'll get tons of false positives as the user has to spot an average of like 3 times each time he spots, and those won't be quiet question marks, they will be spoken and solid icons of soldiers. So then you'll get people spotting an enemy right where they are and taking friendly fire, and just the general annoyance of so many false positives.
At least with the current system if you get these false positives they just show as quiet question marks.
You guys know this is true. How many times have you seen an enemy and it took you like 4 times to spot him because the question marks ended up all over like too far, too close, etc. It happens all the time.
I like this change even when I can't understand what I am saying as the PLA or MEC. I always disliked how in vanilla BF2 you would have some commander who would spot every little unimportant target and you would get his voice repeating "enemy infantry spotted" over and over and over again.