Flamestrike
Legend
On the other hand, at least as expressed in 5e, I think Advantage/Disadvantage is waaaay too much a big blunt object; its even more of one than the modifiers in Mythras, and I tend to find it a bit blunt sometimes. Basically, when you hit "once you have a penalty its this big and there's no bigger or smaller" you've gone too far, IMO.
(That first qualification is because you can have something vaguely like it--SotDL boons and banes, say--and me find it not too much. But this is a case where 5e decided simplicity got to trump any other concern and I can't follow it there).
I hear you, but it's enough for me, especially if they then key special abilities to trigger off the mechanic.
Advantage = +1 die step, Disadvantage = -1 die step. Some combat options (or Edges) then require you to have advantage for them to trigger (or allow you to avoid disadvantage for certain situations).
You might need advantage to make a called shot, and a bipod might cancel out disadvantage for autofire. Aiming might grant advantage to hit, and a scope might cancel disadvantage to shoot at long range. Snapfire might impose disadvantage if you fire and move that turn, and the Steady Hands edge might cancel that disadvantage. Taunting/ Combat tricks vs a creature might grant all attacks against it advantage till the start of your next turn. Etc.
That way its not just a binary disadvantage/ advantage and there is some interplay with the mechanic and 'setting up' a creature for a called shot, or for the triggering of an Edge, and PC's can build around it with Edges etc.