Mmh, i noticed a rather similar post by you on the tyranid board, complaining about how genestealers are cheesy for being better then marines. And now you are complaining that the nightbringer cannot be harmed by your standard marine without special equipment? I do wonder if you are serious in these complaints, or just trying to agitate people on this board, seeing how you start two such complaint posts in a relatively short time.
If you are serious, my apologies. I suggest you look at the role both of these units play within the army they can be fielded. A nightbringing has its advantages, though as a necron player myself I would almost never field it, unless against a fairly novice opponent. Genestealers also have their use, I personally love them, but they are also a very costly investment that can easily be mown down by bolter fire (darn those smurfs being so cheesy, they should be banned from tournaments i say) or an even more expensive investment that can be picked apart by heavy bolters. Both units are extremely good at what they do, but they also have glaring weaknesses, and a rather large pricetag. Think about it, if everything would be homogenized, what would the fun of the game be if the only model you could field would be tactical marines without upgrades?