There are things they had not forseen.
One of the reasons they are making new restrictions is abuse that people are writing about (not here, but Facebook and blog pages).
There are people who have written that they are getting 2 or more DAS cards (some for non-disabled family members, some by lying and saying they lost or forgot their DAS) for up to 6 people each. That way, they can have a DAS Return Time active at all times and basically not have to wait.
So, you can think those type of abusers for new restrictions being placed on people who are trying to work within the system.
Reports are that DL is planning to tie the QR codes on the cards to passes and that WDW will do the same with Magicbands. Until that rolls out, they will do other things, like limit numbers of people.
I'm not sure how they could not foresee this happening, I overheard a 5 year (or so) old ask their mom what would prevent this from happening and I can't believe that a 5 year old is smarter than all of the Disney executives, lawyers, etc. combined.
Even for those of us trying to work within the rules, we have had occasion to both have gotten a return time when one came into the park later than the other, not knowing the other one had gotten one already. We simply didn't use my return time, but I could easily see how this could be abused if someone were to try abusing the system.
I am honestly not sure how tying the QR Codes to a pass will prevent this. For example, there are many times that DW (who needs a DAS for her own needs) goes without me and many times that I (who also need a DAS) go without her or that one of us will want to ride something that the other doesn't. So, you can't say that there can only be one DAS per party. But then how do you prevent both from getting a return time when both that have a DAS are riding while not stopping both from getting return times when both are not riding the same attraction? For example, I want to go on Space Mountain and DW wants to go on Star Tours. I don't want to do Star Tours and she doesn't want to do Space Mountain. So, we would each get a return time for each attraction.
But if we both wanted to do both attraction, there is nothing that would currently stop us from getting return times for both attractions. This obviously is not in line with the spirit of these new cards. But how do you prevent this without preventing the above scenario.
Some will say you would need to divide your group into two cards, but this doesn't work, because if you have a party of 6, there may be times where 4 will want to ride one ride and two another. Then others where it would be 3 and 3 or 5 and 1, etc. And this may not always involve both people with the DAS, so that doesn't work.
Then the fact that they are valid for two weeks at a time means that many people's party size will vary throughout the two weeks. This is more at DL than at WDW, due to the nature of who tends to visit the parks, but it is still an issue. And yes, sometimes that group will include multiple people who need a DAS. In our case, there is the potential that we would have 5 people who all truly NEED a DAS, for varying reasons. And in all of these cases, these people would all show up at different times and would also be going on other days that the others would not. If 5 people in one party needing a DAS seems like a large number, it's not at DL. Keep in mind that many people at DL meet in line while waiting for attractions and end up becoming friends. In this case, since we all had GACs or the equivalent of the time, it's natural that we would have multiple people that have need of a DAS and yet not all show up all of the time, as we would be waiting together, which means that we would naturally meet others that need assistance.
Another example is that one of the people who is frequently in our party cannot ride Tower of Terror due to her needs, but others will wish to do so, including others that need a DAS. So, how would they all go together if say their pass only was valid for 3 people and 4 of the party wished to ride. Then she wants to go on another ride with herself and another person, but couldn't if only one person could have a DAS.
So, I really don't see any way to properly control this that doesn't prevent legitimate uses of the DAS.