It's a double edged sword because I've had DCs call from the booth and their reasoning was they could see the field better. BUT the positives to being on the sideline is direct interaction. Being able to talk to the coach directly and him asking me what did I see or this is what he saw and we can talk about it is priceless.
I can tell you this much, I remember a game we played against Stanford and was getting lit up the 1st 2 drives and I come out and the coach is asking me what do I see and I tell him they're running hitches to both sides and the TE is running a clear out slant and the slot is running 5 yard in and go and they did it 3 times because we're playing off. I tell him they're gonna run it again because we're playing off in case they slant. I tell him let's give them the same look but let us(safeties)crash. He calls the other safety over and then the whole secondary and I tell them what I see. Coach says ok let's do it then from there he tell the linebackers to drop deeper in their zones and what do you know. We get a pick 6 like 4 or 5 plays later. We picked that play off twice because we were able to communicate in real time. That's why I'm a proponent of coaches being on the sidelines.