I believe the people that want the 2mA is to mimic the tritium light level which if I understand there usage would be more for identifying where the light is.
Since this is the low level I believe any LED current in the 10-25mA range would suffice and most users would really care or see any difference. As long as there are other brighter levels in case low is not sufficient.
Remember, these are three regulated levels. Consider all the Alephs out there that use the resistor tailcap to get the low level. The low came at a price of poor efficiency and hard to control what the actual current to the LED was.
With a 10mA drive current to the LED the overhead is another 1mA or so making the converter efficiency in the 70-80% range. A 10 ohm in series with the GD for example might be giving you 1mA to the LED and being out of regulation still drawing some 200mA of current from the battery.
Maybe, the current levels should be more like.
Regular 20mA, 180mA, 700mA (3W version)
Mizer: 10mA, 60-80mA, 350mA (1W version)
The more I think about it... Those that want the 2mA will be custom and not a standard product. For the vast majority 2mA will be too low for practical purposes.
Three levels makes sense for an EDC light. For a throw light it probably makes more sense to having a regular level and a turbo level since the usage will be different than a pocket EDC light.