Storage space for items costs Con and the team money for server storage.
Just some tech stuff.
The data are stored in computers in bits - zeros and ones.
8 bits forms 1 byte
2 bytes forms 1 "short word"
1 byte may store numbers from 0 to 255 (2 in power of 8 minus 1)
1 short word may store numbers from 0 to 65535 (2 in power of 16 minus 1 OR square of 255)
1 long word (2 short words) may store numbers from 0 to 65535*65535 (I don't remember this value, something like 2 or 4 billions)
We have approximately about 2000-3000 of different items. Some items are in counts like components. Some in single units like weapons. Then we allocating 1 short word (2 bytes) for the number (ID) of stored item, and 1 long word (4 bytes) for its counter, regardless of type. It means that the 1000 items inventory will cost 60.000 bytes.
One 3" floppy disk stored from 720.000 to 1.440.000 bytes, or from 12 to 24 such inventories.
Let there are 1M of players on all sites. It gives 60 billions of bytes or 60 gigabytes. Check the capacity of hard disk in your computer. I highly doubt if it is same or smaller. My mobile and tablet both have SD cards with capacity of 64GB. So, we can't seriously talk about the "costs of storing an inventory".
Of course, no one may prevent Con from storing ALL data of the items in every gamer's profile, but it will be a real waste of the computing resources. And I can't imagine that the authors of such successful series of games are too dumb to not optimize the data storage. It is the basics of databases.