If the unit is labeled "airborne" I don't see a reason the size greater than a molecule for why one should have this feature if one can't get the crew down in one piece! I'm not arguing that it's realistic or unrealistic, well I actually am, but if it is a "realistic" feature which has been added by intention, I think that realism could be much more well spent somewhere else.
Why would you buy a tank platoon if the tracks fell apart after 500 metres?
@SC: I think the crews are parachuted separatly, at least in Russia. That, or given great amounts of vodka. (Or maybe both.) Unfortunately, that is impossible to do in winSP, at least to this date.