What I am presenting is a way to prevent those 40 players from trying to purchase the same plot as soon as it is available.
And once again, all this is would do, at best, is partially stifle a symptom, while actually worsening the underlying cause. People stalk plots so much, particularly on certain servers, exactly because there is a shortage of plots to go around. Increasing prices simply puts more buying power in the hands of people with more gil, meaning those with less gil have an even more reduced chance at getting a plot. On many servers practically every district has every plot already taken, meaning a gil increase will just leave the market even more lopsided and inaccessible. This fantasyland you're talking about where suddenly plots open up and timers are able to count down because the property is now even MORE valuable is never going to happen, in fact it's precisely the opposite. Not to mention, as a method of combating RMT? This would literally drive RMT through the roof, because nobody who doesn't already have the cash to throw away is going to grind up 20, 15, or even 10M gil just for a small, instead they'd just buy the gil instead.

I also think you drastically overestimate just how much gil most players have, as well as the overlap between the gil-making community and the lifestyle/RP community. The sorts of people who want to spend their time decorating a house to look like a coffeehouse or sauna and the sorts of people who love to play the marketboard all day probably do not share a large intersection on a Venn diagram. Hell, if the devs just created house-independent gardening, many people would drop their houses outright.

Is it clear now or are you truly incapable of comprehending that the reason why players, like you, feel so entitled to being able to purchase a small house is due to the ridiculously low prices? 20m is nothing in this day and age and a, theoretical, fully devalued plot at 10m would still be very easy to obtain for any player who's even remotely determined to get one.
Sorry, but someone who owns almost fifty houses and a fleet of airships and submersibles complaining about how "entitled" someone is for wanting to be able to purchase even just one small is nothing but laughable.