Draigo is a single character horribly wanked by Ward that is further boosted by being a Grey Knight, the ultimate character in W40K for the most wank. However, Nids, on a whole, are largely beaten down and have poor showings in most works considering, that as something that can only be portrayed as a villain, will almost always lose. Also, 90% of a Space Marine Chapter is a small price to pay for the destruction of an entire Hive Fleet. Very small in fact. As stated previously, the danger of the Tryanids comes not from their lethality, they can be destroyed with sufficient forces. Their danger stems from how they plunge whole sectors of space into darkness as they jam Imperium communications and prevent defensive forces from rallying, and allow other factions to attack the area with little trouble to themselves.