I really didn't understand the issue.

[Eissels]

Many of the threads you're talking about had people explaining what they felt was the harm in it. Just go read them? They're not going to post anything different than what they wrote in those.

I didn't see any reasoning but "SE is selling gil and this feels greedy to me."

No one actually brought up reasons how it hurt the economy, they just accused SE and the people selling the bracelets of being greedy or lazy.

[Ampheni]

-snip-

Because this potentially become a method to turn the game into a pay to win situation.

Now, if you think about it, what does gil can currently do?

You can buy crafted gears, food etc etc with them right?
Now let's say someone have a large amount of real world money, but they spend little efforts in this game, with this item can be bought from a cash shop and be sold to another players for gil, he now have a new way to gain a large amount of gil without putting in a lot of efforts, by spending real world money.

With these gil he earned, he can buy high level crafted gears, super rare materias with minimal efforts, as long as he have the real life money to spend.

This could potentially makes the in game economy affected by the real world's economy, and this leaves the players who is not willing to pay extra real life money yet put in a lot of in game efforts a bitter taste that people who are richer can always have the upper-hand in-game.

[Squintina]

I didn't see any reasoning but "SE is selling gil and this feels greedy to me."

No one actually brought up reasons how it hurt the economy, they just accused SE and the people selling the bracelets of being greedy or lazy.

Then you either didn't read, or you read selectively because I've seen a bunch of reasons beyond just "SE and the people selling the bracelets are greedy or lazy". Go read again.