While I have heard many ideas for limited storage expansion from Gaile, I beleive it would be foolish of Anet to do very much of that type of thing strictly from a bussiness aspect.
With the current system you have a fairly small amout of storage so you must be more selective about what you keep..Prevents large scale hoarding of many things by players.
Also since they do not charge a monthly fee for this game but continue to expand update and maintain this game very well, small storage space is one way they can continue to fund the game and continue to do great upkeep and still make a profit.
I have a second acct that is used just for storage and didn't mind buying the second copy considering that it costs nothing to play and as long as Anet is making money they will continue to operate a great game