For me there were two concerns with this very short cooldown on transfers.
1) Increased likelihood to Grief / Ninja on a fresh server (there were already a lot of people who would transfer, build a fresh linkshell, get priority on a relic or mythic farm with promise that the guild as a whole would pursue them for everyone, then have the person server swap and do it again after getting a complete weapon. I've personally seen a few people do this, one person in particular comes to mind whom was not afraid to take advantage of everyone and everything around them to accomplish his goals. This scars the community in terrible ways, because now that person isn't just walking the server he screwed people in freely but unable to participate in future-large-scale events because people know him to have manipulated the masses, he instead gets to transfer entirely off server, repeat the process, and feel like a hero 100% of the time, with the only negative repercussion being a small transfer fee when the time came.
2) Market disruption. When we see in the news talks of how the economy of the world is largely controlled by the richest 1-5% of people, it can be a little scary to think about. In a game world like FFXI, there isn't a natural stability, since everything is virtual, there is no limit to the amount of market supply for products except those imposed by artificial time sinks. "Resources" will never run out like they would in the real world. As a result a wealthy enough player could create a drastic shift in those time-sink driven values and alter their worth heavily, creating a sudden uncontrollable demand in one server where some of these items are extremely cheap relative to another server, and altering the market (and whatever particular elements of the game those marketed items also happen to impact on existential levels), while creating a potentially incredible influx of profit for one person in a matter of 6 days time to fruition.
But... upon further examination, it's a damned if you do, damned if you don't scenario.
in regards to #1)
Griefers will always grief, and given enough time, they would probably find ways to take advantage of large groups of people no matter what.
in regards to #2)
By now, every major MMO game that uses separated servers to store character information should have plenty of capability for cross-server markets, just as many have cross-server instancing. There is no excuse for markets to fluctuate from server to server at all, just because of the interests of the players on that particular cluster. Let everyone contribute to FFXI's global market stability so players can quickly establish more accurate value and worth to the items we buy and sell. It's wrong of the developers to charge such a fee for a service that, in my opinion, should be completely free. If that fee is in regards to the technology that was used in the creation of the transfer process, then I would argue customers already pay a monthly fee... so why limit people from playing with one another at all... especially when you obviously have the near-instant capability of allowing us to play with one another for that nominal 18 dollar fee?
These are just my opinions, but I would define Name changes, Server changes, Race changes, etc all to be standard service options. Charging extra for these so called "features" is simply introducing Micro-Transaction based income into a game entirely designed around non-micro-transactional services, favoring monthly fees so players don't have to deal with that crap.