I've been thinking about this, I think it would be a cool idea. Having like an animated skin on your weapon, take something like the AWP Lightning Strike from CSGO, except it's animated. I think if this idea was considered, it would have to be from say.. events or special time events. This would make it so everyone doesn't abandon the paints and tints we have at the moment.
I think we should get more customisation for our weapons, and have a better looking effect on it. I am aware that planetary weapons give some rainbow effect but they're hard to get.