So it boils down to limited instances of land; how many total plots for each size are available per server are we talking about here?
The problem with this entire housing fiasco is the simple requirement for buying land ie: only gils and rank 6.

If there are more requirements like number of memberships and number of FC points for each size of land then there would be less chances of hogging.
For example, make it so that Medium requires at least 100 members and 1mil FC points, and Large requires at least 300 members and 2 mil FC points. Get those data and see how many FCs are eligible and price the lands out accordingly.

Using only 1 unit of measure (ie: gils) cannot be a true reflection of Free Companies where there are much more dynamics involved than just wealth.