Pay for your inventory.

[raelgun]

Okay.

Those are a few examples. Can name more if they aren't enough.

So basically, you want to break the glamour market right?

Those games also don't have a lot of meat into the game, this one actually does, you have mentioned a lot of niche games if I'm honest with a small active playerbase that will make active use of the inventory space, free to play games do not have a large amount of active players that invest into it in the long term.

This game has a lot of active players concurrently using its storage servers.
Blizzard is a powerhouse amongst the industry and is literally made of money.

You can be damn sure if all those games you mentioned had a large active concurrent playerbase using all that inventory at the same time they will not handle it.