Originally Posted by TryHard

Is it necessary, no. Does, IMO, it make the car better to drive, yes. (Did the same thing when running the Tamiya, so it's nothing new).
It's not a difficult thing to do, just need a small drill bit, and drill a small hole in the plastic cap piece, so that the air above the bladder can vent out. This also helps to remove a bit of pack from the shock too, which for high speed damping is no bad thing.

Regards
Ed