Well, I read that response of Fluke as quite clear, albeit politically correct ;-)
Reading between the lines, they state that:
- 77 and 177 have the same guts, except the RMS circuit/behaviour
- military (and probably government) are the main customers for the 77
- because most users are more happy with a DMM that can measure RMS (at least, for the same or lower price...)
Judging from that: Probably the amount of devices manufactured and sold are less than of tha 177, so the fixed costs are to be distributed to fewer units. And: If the military needs them, they probably are prepared to pay a premium for them.
Eventually Fluke has to guarantee some extended time for spare parts or whatever, this might also be of concern for some pricing decisions...
The point here ist, that as stated above: When a certain amount of processes and paper for them have been defined, changing them is not cheap. Someone has to change them, evaluate the usage of a RMS multimeter in them, check for a different behaviour and consequences, and therefore there will be some kind of liability for damages arising from this.
So it is cheaper to leave things as they are and continue to buy non-RMS Multimeters instead, that behave exactly as the models before.