I don't mind the "death by a thousand cuts" style for assassinations. That's kind of has to happen because of poison applications and the whole fact that it's based around daggers, and that is essentially what they do. I think perhaps to begin with, daggers were designed more to give more crit but less average damage, that kind of went out the window a long time ago however. That's why we had abilities such as backstab and talents like lethality which are long since gone/dissolved. In reality they probably wern't much of a dps boost, but lethality felt cool as a talent.
The only way you'll lower the passive damage is to remove slice and dice from combat + Sub. Many people are scared of this idea, it's an outright damage nerf, it slows us down, but it could make way for larger damage increases. If it was done properly, it wouldn't be a DPS loss. However, knowing bliz and theyre hatered for rogue balance, I can imagine them just removing snd and then only bumping sinister strike damage by ~10% which wouldn't be enough to compensate.
If this approach was to work, it would need for the energy system to be overhauled and sinister strike to be cheaper.Energy regeneration would need to be addressed again.