All I know is that it helped commanders command on the battlefield but was this worth having soldiers running around in bright red? especially in harsh wooded terrain where local militia and indians easily blend in and often snipe them?
There are several answers about this in the past. I'd recommend going through them. If you have any other follow up questions, I'll be happy to answer but the simple answer is that they're like that to create a regimental unity and to show which side they're on.