I was reading the log post about the Beach Club review,
http://www.disunplugged.com/2010/09/07/review-disneys-beach-club-resort/ , and I think this observation sums up resort shopping:
The one observation I'll make is that even when they had more resort-specific stuff than they do today, the comment I read over and over again was "I wish they had more unique items...I'm tired of the same old boring stuff."
I'm sure it is cheaper per-piece to do a run of 15,000 t-shirts than it is to print 5,000 shirts. The problem is, if you took the comments here to be indicative of DVC members as a whole, even the 5,000 isn't good enough. Instead Disney would need to produce 500 blue, 500 pink, 500 gray, 500 short sleeve, 500 long sleeve, 500 crew neck, 500 v-neck, mens styles, womens styles and on, and on, and on.
We used to frequent the Disney outlet stores around Orlando and the one thing that we ALWAYS saw in stock were resort-specific shirts marked-down 50% or more because they didn't sell at the resort gift shops.
If they print generic stuff in moderate quantities, folks turn up their noses and say "I'm tired of the boring designs." If they print more specialized designs in smaller quantities, it ties-up more shelf space and the buyer market for each item is even smaller.
Probably the best we could ever hope for is some sort of design-your-own-shirt kiosk or mail order service. That way people can choose their own sizes, colors & garment styles, and have a selection of imprints available.
I would never dream of buying a generic "Walt Disney World 2010" shirt, or anything like that. But I can tell you that I see people walking around in those shirts when I'm outside of the Disney parks. By comparison, I have NEVER seen anyone outside of WDW wearing a shirt that says BoardWalk or Beach Club. We may not like those generic character designs but apparently someone does.