Actually, if GW really wanted your money and tried to get you to buy it for such a reason, the Wraithknight would have amazing rules ala the Heldrake. I'm happy that it is a good, but not must-take, choice.
Well, it is very strong in melee - where cover doesn't matter - and sometimes it may not be possible to get into terrain without sacrificing your shooting.
Blind works against Initiative, and the entire army - aside from Wraith constructs - is I5, meaning they only ever fail on a 6. Even Wraith units only fail on a 5. Blind is designed with (non-Battlesuit) Tau/Orks/Necrons in mind. Plus, Blind tests are resolved per unit, not per model, so it isn't like you have to take many anyway.