Voted No with exceptions.
These are military machines made to survive an extremely harsh battlefield environment. Adding various colored neon running lights to their weaponry that shows up at long range only advertises to the enemy exactly where you are regardless of your mechs state (Powered down, passive, moving toward an objective etc.) As well as advertising what weapons they have and leaves out the surprise the player will have encountering a specific variant or custom mech.
Once you learn the color code and the banding of the weapons, you already have the info to defeat the mech at range. When we played online years ago, you learned what the enemy had by the weapon firing by itself, the specific signatures of certain weaponry was learned from actual gameplay and experience. I also would take advantage of certain mechs at long range that advertised their presence in prior games with a mismatching camo scheme to the terrain, and at night with a weapon that glowed prior to firing (Think Bombast Laser in MW4)
But those above examples are fine, they are the result of the players choices for their mech, the camo scheme was a choice to advertise, and the Bombast laser was a choice in weaponry that had a specific weapon signature. To not allow the player to have a choice in hiding their weapon config and to conceal their presense and to surprise the enemy just doesn't seem right to me. It's a part of the Battletech universe to have surprises, pleasent and unpleasant. Plus with the great system this sim has of showing the actual weapon on the mech, it's more fun to look at and figure out the loadout by visual analysis, as they get closer to you or fire the weapon at others, without having to advertise the weapon with a specific glowing light that's visible from long range. Like the others have suggested, the PPC should emit a bluish light at the muzzle as was described in the books, and other systems could have similar effects if warranted, but I just can't get into the idea of lights on the side of the weapon.
Just my opinion based on my online experiences.
