Yeah, I don't understand these limitations.
If I am limited to one house on the server on my account, then all my characters on my account should have full access to the house.
And I would also like if they made it easier to transfer items and gil between characters on the same account and on the same server without having to bother a friend to help trade items over.
I would like some sort of account-wide bank, similar to the FC chest but shared across all your characters on that server. You could put some gil and items in there and then all your characters could withdraw.