I don't have an easy universal solution. That was my point. There is not one solution that works for everyone. Occasionally guests do need more than the "wait elsewhere" pass. Disney acknowledges this, and says accommodations can be made, but there is no formal process to follow. I think this should be clearer. There are issues with identifying visitors who truly need extra accommodations (beyond the
DAS card), but it is certainly not impossible. A limited number of instant access passes (3-5 per eligible guest), maybe even for a single favorite ride (which are usually not top tier!), should have minimal impact on other guests. This would be much lower than 1% of the guests, could be factored into the computerized crowd distribution system, and never noticed by other guests.
For those who don't think it is fair for a child with special needs to receive a reasonable accommodation, go spend a couple hours sitting in the OT/PT waiting room of your local children's hospital. Every week as we take our own kids to therapy, we are reminded how unfair life is and how lucky we are. Others have it so much worse! Can you imagine spending 30 minutes in an elevator with 20 strangers from different countries, each with different smells, and speaking different languages. That might be what it is like for my kids like my son waiting in line. He is hypersensitive to stimuli like sounds, smells, and visual effects. They also often have no concept of time or personal space.
For those of you who don't understand why a parent would even try to attempt Disney, knowing how difficult it is likely to be for our kids, I promise that the moments of bliss are irreplaceable. My son loves Pluto more than anything else in the world. Pluto is included in his night-time prayers for happy dreams. He LOVES Disney, and I would do anything in the world to give him those moments of joy. There is SO much he cannot do, that these things he can are even more valuable.
I can tell you that the new Fastpass+ system is worthless for my family. I got up at midnight to make our reservations for all of our family favorites. Unfortunately, we were not able to force him into such a rigid schedule. I cannot tell you how many times we swapped top coaster reservations for things most people skip--Space Mountain for Magic Carpets of Aladdin, anyone! The DAS card allowed us to make more reasonable plans based on his mood and abilities that day--but even then we crossed off 7DMT for Tomorrowland Speedway, even though we had waited almost the full time, twice.

It would be great if the pass could be signed for two rides, instead of only one at a time, but I can see how this would be an extra advantage and make the system more prone to abuse.
For suggestions to improve the current DAS card experience...
1. Walking the child over to the ride to get the pass signed is usually just setting us up for failure. For most of these kids, walking up to Dumbo, then walking away and trying to come back later is torture. Many have no concept of time (10 minutes = 2 hours = next year) and limited cognitive abilities to understand the process as a whole. Whenever possible, one parent goes over to the ride while the other waits with the child somewhere else, but this assumes that there is always an extra parent and involves lots of running back and forth between 'lands'. With all the technology, it would be great if we could get the pass signed for any ride by any attendant. They just need iPads with updated wait times.
2. Allow guests to have the pass signed, even when the posted wait time is short. If the posted wait time is 15 min or less, they would not sign the pass. We tried to run to Tomorrowland Speedway after the night parade, but still we were behind a mob. The posted wait time was 10 min, but the line was clearly 30-45 min. I waited 10 mintues for the posted wait time to change before the cast members could give him a return time. We also had issues when we sent someone ahead to have the pass signed, but the line was too short. Then by the time he arrived, it could be much longer. Then we had to get the pass signed and stall him some more.
3. Allow guests to use the FP line, even when the wait line is shorter. My son is a creature of habit. If he enters the ride through the FP line once, he does not understand going in a different way the next time. Also, the traditional lines sometimes have extra components that are more stimulating or distracting. Even when you can walk right on through the regular line, sometimes we have legitimate reasons for requesting access through the FP line.
4. The pass only works on attractions with a FastPass line. Did I mention that my son loves Pluto, a character who does not have FP at MK. Neither does Donald or Goofy. We were surprised how many times we had to wait in lines for characters and less popular attractions. It would be great to travel at less crowded times, but unfortunately we are tied to the school calendar. During our times waiting in line, we figured out easy alternates for a DAS line to some of these. Disney could too, if they tried.
Disney met with Autism advocacy groups (among others) before rolling out the new system but chose not to incorporate many of the suggestions. If you have never worked with these kids, you might not see why it makes a difference. It does. I am SO thankful for all that Disney does to accommodate our special kids, but a few little changes could dramatically improve their experience without any noticeable effect on other guests.