As a user, when I want to manual run the sprinklers, I want them to turn on. I really don't care about the state of the rain sensor. For example, if it's hot out, and my kids want to run through the sprinklers, I want to be able to turn them on, even if the rain sensor is still wet from a light rain that we had a few hours ago. It's frustrating needing to disable the rain sensor and re-enable it when I'm done.
One day I woke up and didn't realize that it had rained in the morning. I tried to manually run a sprinkler and it didn't work. I went around inspecting my system for 45 minutes thinking it was broken. The app would start the zone and quickly stop it, without giving you a reason. I was about to start taking things apart and then I thought about the rain sensor...I disabled it in the Rachio app and then was able to run the zone. It would have been nice to get a message with the reason why the zone immediately stopped, or some kind of an indicator on the Rachio home screen showing that it had triggered. It's confusing for the use when the zone run starts and then instantly stops.
In the end, I think the most user friendly solution is to just automatically bypass the rain sensor on manual runs. It's just less thinking and troubleshooting for the end user.
On a side note, it would also be nice to have an option for a scheduled run to override the rain sensor. I have a special case where I have a specific schedule for a zone that fills my pond. (My small pond has a fountain and on hot days, it runs the water level down by about 4-6 inches each day. I have a daily schedule set to supply 3 minutes of water, which will top off the pond.) It never rains enough to naturally recover that 4-6 inches in the pond, so when the rain sensor triggers, my pond refill doesn't run and my pond goes low every time. Then I have to disable the rain sensor in the Rachio app, manually run the pond zone, and re-enable the rain sensor. It would be nice if the water intelligence switch for the schedule or zone could bypass the rain sensor. Or if there was an additional switch.