#1 - July 6, 2012, 1:05 a.m.
A total redesign is not something that will be considered but small tweaks that elegantly solve the problem may give the devs insight into the why of the problem and may even result in a resolution. It is highly preferable to look for pure QoL changes rather than buffs.
Some starters:
This one was proposed by Slant;
Turn Soul Reaper into a refreshing DOT that ticks every 6 seconds and only does damage on a target sub 35%. Every time you use it on a target it extends the time by 6 seconds up to a maximum of 18 seconds. The cooldown would also have to be removed and as compensation a limitation of only 1 target being debuffed at a time (like how Devouring Plague or Curse of Doom operates) would be added on.
This would also have the effect of minimizing the "skill cap" as well as marginalizing the effect of BT generating Death Runes compared to RC and RE. In PvP you would still be able to dispel the entire thing with a single dispel so no buffs there. Death Knights also have no interaction between DOTs and Haste so again, not a buff.
Change the cost of Soul Reaper to be spec specific;
For Unholy = Unholy Rune cost.
For Blood = Blood Rune cost.
For Frost = Frost Rune cost.
This would have the effect of making the costs more in line with how the specs currently operate rather than the "square peg in round hole" syndrome we are looking at now. As well this also marginalizes the effect of BT in which Death Runes are not as valuable in relation to total runes generated.