I've been lurking here awhile as this is a subject close to my heart and I suspect there will be a point where market pressure will dictate a second (or more Genies) per a single residential account will become a normal thing. I would second the opinion that additional ones should not be free but then I have "purchased" nearly all of my DVRs in order to ensure I got the model number I wanted and not some twice cooked HR21 that needs oxygen just to get through the day:)
My speculation on the matter is until they have reached a particular saturation/stockpile trigger point they are considering the "new" goodies should be spread around and not hoarded by us obsessive compulsive types.
Other speculations of mine see the Genie and 3 clients as a result of a marketing spreadsheet exercise (probably if you take all the receivers in residential accounts using DVRs and divide by the number of accounts you would get some 2.6 or some fractional value > 2 and <= 3). Given they had to cook up this new technical landscape targeted to the spreadsheet AND were highly deadline driven, it is considerably likely that the firmware (and mother ship billing software) were focused on this theoretical "Whole Home" deployment scaling. Building in to allow an account running multiple Genie's each possibly running multiple clients was not built into the products DNA for the initial release.
Meanwhile marketing moves forward with other new shiny things (read wireless clients, sports searches, HD Apps, etc) and these advancements stall going back and altering the base operational functionality to encapsulate more than one Genie. (and with some marketing model as a target basis, there is likely no real motivation to review that limitation at this time). Eventually pressure from the subscriber base may motivate that change but it would seem new shiny things and functionality seem to be the priority at present.
I personally want to architect my infrastructure to handle more than 2 Genies with some clients while still retaining several traditional 2 tuner DVRs in some locations, and perhaps several normal single tuner HD receivers for the guest rooms. I look forward to that becoming a reality someday but in the meantime. . .
Don "please note these are my speculations and may or may not have any basis in reality whatsoever (sort of like me )" Bolton