Disney never expects or intends for AP passes to be used for the bulk, or even a majority, of the days of the year. Hence its discount pricing (an AP becomes the better option over hoppers, or regular daily admission, once you go past a certain number of days).
A transferable AP pass could be passed around to enough people so as to allow admission for a large number of the 366 days. You can only use a hopper for the days on the hopper, and Disney assumes that the purchaser will actually use all the days on the pass (thus, unused days are good forever). Thus, if Disney were to allow transferability of tickets, transferability of an AP would have a materially greater effect on crowds and ticket profits than allowing people to use all the days in a hopper (since WDW assumed that all the hopper days would be used anyway). That's probably one of the reasons why Disney didn't impose scanning on hoppers, while doing so on APs.
Non-transferability is usually meant to inhibit the black market (scalping, third party sales, etc.), which is probably the reason why Disney's doing it now.
Of course, Disney has a right to scan the hopper users, they own the park. But the fact that a hopper can be used forever loses some of its appeal if you think that you won't be able to give (not sell) your unused hoppers to someone who can really use the days left over when you won't.
I know that when I bought my mom's and sister's, I assumed that I could use any unused days (for bad weather or if we were tired) on another trip with just my sister. It motivated my purchase, I paid the asking price, and the we would definitely pay for extra days, rooms, food, and services.
In a way, Disney enforcement of the policy is raising the prices, and stakes, on your hoppers: you are taking a higher risk of having unplanned and unused days on your hopper that neither you, nor other people, may be able to use. And you paid close to full price for the per day privilege.
On a slightly unrelated note-- of course, if you don't like a policy you don't have to go. Notably, although Disney prints non-transferable language on the back of their ticket, their new scan system allows for people to interchange tickets, even give all unused ones to one person if they were bought/activated at the same time. So, really, it doesn't seem like they really are wed to the one ticket/one person thing. It seems to acknowledge that people plan trips as families and with a budget in mind, not as individual ticket purchasers. The new system closes an avenue for keeping your Disney vacation affordable if they aren't activated at the same time--i.e., families arriving on different dates-- you're out of luck in exchanging, even with the new tracking system.
A WDW hopper is a contract between you and Disney, but our only negotiation tool is..not going. And for some of us, simply not going is not an option. We should be able to at least complain about it and wonder the whys and wherefores...it's pretty much the only thing we can do, really
I'm not sure what I think yet.
