I suspect that demographics has a lot to do with it - ie. a lot of members either don't have rugrats or have gotten rid of them, but if we're intent on changing RA as we currently know it, why stick to 1 passenger only? No-one seems to question that limitation and yet they are (theoretically) prepared to accept that a couple of tons of AN2 is ok:loopy:
I can tell you, being able to stick my wife and youngster in a J450 and operate it at 700kg would make the world of difference to my flying and is the reason I am currently casting my eye further afield, much as I don't want to get involved with the whole CASA system.
If 700 or 760kg is to be classed as RA, I find it difficult to accept that an appropriate adjustment to the annual fee to cover increased insurance costs for the extra passenger(s), wouldn't address any realistic drawbacks for those who don't want the extra capacity.
PS. I don't realistically expect that we'll see the above in my lifetime, if ever, but I'm equally unconvinced of the logic of "needing" more than 600kg anyway - Jabirus, Morgans, Cubs, Savannahs and Foxbats seem able to build reasonably robust aircraft at 600kg, I'd submit if others cannot, then they're doing it wrong.