Reaping helps more than just 1ss>2bs lols, bone armor, ghoul enrage(your ghoul dies? try ernage him
(needs U(D) rune - breaks your rotation), call him back
(cooldown begins upon ghoul death), deathcoil him sometimes maybe??
(DPS loss)), those use unholy runes which are for ss... how can you not see that? ss is top damager and if you lose one each 30 secs(and more) how can you expect to do decent damage?
(by using the most underused DK spell - Blood Tap) with reaping you actually GAIN some more ss over time using both blood(death) runes.
(which is exactly why you shouldn't pick Ghoul Frenzy, so you can use those 2 D runes for SS instead of Ghoul Frenzy + Blood Strike. As I said, Reaping is only better if SS>2xBS - otherwise Unholy Blight and Dirge are way better) Use damn glyph of ghoul.
Edit: Ghoul is 10-15% of total damage[depends on encounter] for 4 points, please tell me whicth talents give more than that ffs
(That's true, and an UDK should always spend those 3 TPs for getting the ghoul as a pet. Alas, if only it didn't die 10-15 sec into most fights on Warmane)