I've asked for JumpEfficiencyDistanceRange since buffs were introduced. Frankly, since fuel cost, fuel usage etc. all have been nerfed and finally dropped last year making better FTL doesn't matter any more (until economy becomes a thing). So it's been low priority.
FtlFuelCostPerMass, FtlFuelCostPerMassDistance and FtlDistanceExponent apply to all which means making them become an individual thing tied to different parts means a complete rewrite of the system. Since displacement/blink/hop drive are going to be added soon this is probably the only and best time to hope for a change. If not it probably won't happen.