Power Consumption: Not an issue
Over-lighting the Environment in the Dark: Not an issue (extremely diffused light)
Need for a way to communicate controller ID: Could have used a more subtle solution, but not a big deal.
If players pitch a fit about it, I'm sure they'll enable some way to limit the use of the controller's LED. That said, I think people are simply worried about things they're not sure of, and rightfully so. In the end, I believe the pro's way out weigh any con's and the con's are nowhere as prominent as those who may currently fear they are.