With all due respect, this is a "you reap what you sow" outcome. There were posts during beta that asked for a full gil wipe rather than redenomination, as some felt there were still going to be issues with gil quantities carried over once ARR launched (not counting steps taken by the developers to remove gil from the economy, which admitedly I did not see coming). People were against it, forgetting legacy players already had an advantage via leveled classes and items in their inventories.
I remember going into one such thread and telling people the story of the Grim Collector bug as well as explain why a wipe makes sense to balance things out. The replies I got included "I don't care about what happened in the past", despite
the famous saying. All because they wanted to keep their stored millions of gil. And I don't doubt that had a part to play in how housing prices are set.
I was on Balmung prior to 2.0, so I do remember how much gil was floating around. I also remember a whole bunch of tricks and exploits for making gil. Some became public knowledge (and were nerfed when they did) before The Calamity, and the lingering questions few dared to ask were how long those tricks had been around and how much gil RMT might have stockpiled because of them.
With this in mind, is it surprising that the groups with the most expensive plots include high population legacy servers? Not one bit.
To answer you claim on fairness, I don't call them fair, but do see why the prices were set they way they were.