Pay for your inventory.

[Fyce]

And that is why you clear out the old stuff to get room for the new.

No, I will not throw away all these event items and the ones filled with memories like my very first Allagan Weapon, dropped on my very first T5 down.
I'll also not throw away all these materias I have just because Lv.V is on the way.
Same, that pre-50 gear is staying with me since I still have to level some crafting classes (which is also why I won't throw away old "junk mats", because I'll need them) and because the new classes are Lv30.

You cannot just throw away everything and call it a day.

Seriously tho', why the hell don't you want free inventory space? In what way will that harm you?
Everyone against the idea of free inventory space just sounds like they are saying something like this: "I don't want to end world hunger because I have enough things to eat already, thank you very much."

This is why we can't have nice things.