I'll do some math to show you where I'm coming from. I will be making a couple of assumptions.
1.
DAS and the Bathroom Pass both work as intended and both times we board the ride at exactly 60 min.
2. My family tours the park as normal, which means we are together unless we are in the bathroom or in line for the bathroom.
3. I only have to make 1 run to the bathroom in either scenario.
4. DAS is obtained for my bathroom issues.
5 Assuming the bathroom pass is where you leave the line and rejoin your family on the loading platform.
I have a DAS and obtain a return time for RoRT, and we go off together, to wait for our return time. We find the nearest bathroom and we hang in that area. At the 15min mark I need to run to the bathroom. As in your example, above there is no line for the bathroom. I take 10min in the bathroom and rejoin my family. We finish our wait and return to RoRT, join the line, and board right at the 60min wait time that was posted when I obtained the return time.
Total time waited for the ride 60min.
Total time away from my family 10 min.
I obtain and bathroom pass and join the same 60min line for RoRT. Again at the 15 min mark I have to run to the bathroom. I take 10min in the bathroom and return to the ride to wait for my family to meet me on the loading platform. At the 60 min mark, I am reunited with my family on the loading platform and we board the ride.
Total time waited for the ride 60 min.
Total time away from my family 45min.
Total time in the bathroom 10min.
In both cases my whole family waits the 60 min. to board, just like anyone else with a DAS. We are together for 50min of that 60min wait, we just wait outside of the actual queue. With the bathroom pass we are only together for 15mins of the 60min wait. The remaining 45 min, my family is in the actual queue and I am waiting somewhere else. Of those 45 min, only 10 are spent with me in the bathroom. So I am separated from my family for an additional 35 mins with the bathroom pass that doesn't happen with the DAS. While 35 mins may not seem like a lot of time, that is just for 1 ride. The additional time spent away from my family increases each time I have to use the bathroom pass. Over the course of a week long vacation that can add up to a significant amount of time away from my family that those with the DAS don't have to experience.