Ask yourself. What will motivate a company more from the following options:
"I want you to make this new item for free!"
"I'm willing to pay for this new item if you'll make it!"
And now you have your answer why people make threads like this.
Actually, they aren't. If you have never bought a single thing from the mogstation, but subbed for a year. You'll have only earned Square $155.88 with an entry sub. Comparatively, someone who bought Sleipnir, Fat Moogle, Lightning's outfit and five fantastas will have brought in $269.87 with the very same sub. You may dislike whales, but from a purely business perspective, they can bring in more money than a sub ever will. In fact, F2P games absolutely dwarf the profit margin of sub models-- by several hundred million.