At the risk of posting in a thread with some rather extreme opinions, let me see if I can summarize 10+ years worth of MMO debates over gil selling and buying.
On the other hand, there is a point where the demands of an MMO outpace what a normal player can contribute. For example, let's say you have progressed to Endgame, farmed legitimately for all of your current gear for endless hours, and are now at a point where the next step up for equipment will take you 100+ hours, per piece, to farm gil yourself. Furthermore, the next level of Endgame content requires that armor/equipment/food just to get in the door. So now you have to decide, if further farming is not your thing, you can just quit the game. Goodbye, all done. OR, you can spend some of your own money, take the risk to your account (which is otherwise useless if you quit) and buy the gear you need to participate in the next level of Endgame content. Spend $60 for a month or two of additional game play fun? That is the going rate for video game fun anyway, is it not?
In conclusion, no one really knows what the End-Endgame content in FFXIV is like. Do you absolutely need double melded Equipment and Materia IV to win? I'm not talking about the current content. I can tell you now that you can EARN everything you need in a reasonable amount of time to participate in the content that is currently available. Anyone buying gil at this time just wants that shiny bling-bling now, now, NOW!
But one day, will they make content that is extremely demanding in Equipment Requirements in order to keep the super Hardcore busy? Probably.
Will Casual players want to participate too? Probably.
And the Gil sellers will be there to make it happen.
My advice is: Don't Panic. Settle down, learn to use your /blacklist. Let SE catch up on their task force to minimize in-game advertisements and irritation. (That was not a priority last week if you remember correctly.) Enjoy the game the way you play it, and grudgingly accept that other people have different priorities. It's going to be ok.