I've always found it cool and funny. The falling comm bursts in like "oopps I'm late guys, did I miss anything?"
Edit: Also the falling animation seems quite fast, I'd estimate it to be around 3 seconds, 5 sec at most. Accurate data pending.
Edit2: A bigger deal than the animation is losing the income from the first 30(?) seconds of the game when the comm is waiting to be spawned.
So in this light would make sense to just insta-spawn the latecomer comms the same time as other comms, and (temporarily) give them away. Having to settle with the default comm doesn't matter as much as losing the income.
Optimally players could select and pre-configure their default commander loadout.