It's not just that they die easily, for 200+ points what do you really get out of them?
Next to nothing, a few shots and then a loss of 200 points. They just aren't economic like the attack bikes are.
Dark Angels 1750 win/loss Record
Win - 23 (Belial helped wreck Ryan's puny Eldar)
Loss - 13 (Brice's Necrons wiped me)
Draw - 2 (The 13th hold out in alpha take and hold)