Erm... huh? I'm firmly against twinking myself, and storing that many items for a guild does seem to suggest just that. I'm not accusing or making a judgement call, but it does seem a bit overboard. I'm an advocate of people earning their stuff, but I also support in game economies to a point (as Castanova wrote of). Even so, a cluttered guild house sounds like someone needs to clean the house rather than worry about more shelves.
After all, things do spawn. That's how you got them in the first place. There is no shortage of cool stuff being spawned that I know of... unless you count when the server is down... ;-) Not my guild, not my problem, but my vote is that huge capacity storage is not necessary. Player discretion in what is kept is - and with a guild, doubly so.