You would have to consider that using new factors means that these new factors will in turn be abused. A lot of this site alone is on "abuse of systems" to but it bluntly. The black hat term itself is of that essence.
Now if you start requiring reputation to get in to Jr. VIP that could make people go around begging for rep. Begging... for reputation, sad as it is Im sure it would happen. Now also consider that reputation (in its literal aspect) would be two sided. One person could have "good" reputation while another has "bad". This site doesnt go into that so I wont either, but it does lead me to a point.
I work 60+ hours a week... not doing this. It pays for me, my son, and my wife to live. She doesnt have to work so that she can take care of our son (and in early November both our children). So what I do NOT have is time, I cant research near as well as I would like. This also includes things like searching through forums, yes I do the general searches but a lot of times information is dug deep... deeper than I have time to dig. What I do have is, drive, intelligence and some money. So while I get started on everything I end up having to (sadly) ask a lot of noob questions because I dont have the time to get that done. My time is overly precious to me because of that.
Now if I would have to wait 6 months and try to earn a certain amount of reputation that isnt a horrible thing to me, as my pace is slow. Except that reputation will be hard to get if I dont have the time to throw out "gems" (as one person called them earlier) which could or could not get me reputation.
So Im starting to ramble... my point is : There is a lot more to consider than just "raising the bar" as the bar for everyone should be pretty different. I have my advantages and my disadvantages which are different than the person who post above me and below me. So something like you are suggesting could help "thin the heard" but is it really good to do that at the "Jr VIP" level? Or should the bar be low enough for people who have interest and drive to get in. Let time, reputation, etc be a part of something that is bigger than just the JR VIP.