Shadowood, just think about what you are saying. The way that you are saying it is that if you give 100 gold to some place, then 20 people would come join there. While I do not think that this is the way that they meant to set it up, it is somewhat set on how many people might come there for work or because of the greatness of a place based on how much investment is put into place. Think about how people want to move to certain places because they are a good place to live or because they could get a job there. 20 people moving because 100 gold is invested is ridiculous. That is not enough gold to support the increased needs of a place (work, infrastructure, etc.).
The ~1% currently makes sense that there would be a small growth on a place because of investment there. What Mel said makes sense in that if someone is really influential, then they could probably make people move or make people want to move. If Sir Richard Branson, of Virgin Group and other things, put investment into an area, then that would lead more people to go there than if I put some investment into an area. What Mel said would result in about 10% of the influence going into population at lvl 20, which may work out. That may still be too strong, but it makes more sense than 20% at lvl 20.
Slindur