Park exclusive items are neat, and should remain park exclusive. That doesn't mean that steps shouldn't be taken to minimize the mass-item ebay resellers.
Disney should certainly limit the purchase number per guest and ask for photo-id in association with both physical address and phone number to be scanned & retained for certain items. Any tickets linked together via Genie are considered "together".
Then, (just and idea) disincentivize resellers by eroding their profits/making it unprofitable to mass-buy. Allow say...five of each item...BUT the price doubles after the first item, second, etc. So:
1st costs $10
2nd: $20
3rd: $40
4th: $80
5th: $160
Then, if a family really, really needs to buy a few of an exclusive for kid's, etc....they are able to but have to pay more for it. You have access to the item, but that doesn't guarantee you get it for the most inexpensive amount.