They don't care, they got their marathon money. If you look at a Disney map, closing that road totally cuts off the AKL from the rest of the property.
So did you end up on Sherberth?
Osceola is a pretty common one for them to use, so I bet any backroads you were pointed to were commonly used for the race days/nights. But I imagine that any given person doing the pointing could have been their first time doing it.
If you think they won't care, then why would you find a person to complain to. Write to rundisney's email address, give them info on how EXACTLY it was difficult for you, and how EXACTLY they could have made it easier.
I know that when we stayed at AKL once the communication was horrid, simply about the fact that the van going back and forth between Jambo and Kidani stops going at a certain time of night. They KNEW when our ADRs were for, KNEW we had a 7 year old with us, and KNEW that it was literally just a few degrees above freezing. And they didn't tell us that by the time we had checked in for our ADR at Sanaa the vans would stop running. Because they didn't share that tidbit with us, we left the car in the Jambo lot, took the shuttle, and came out to a mystery as to how we would get back. We had only checked in a few hours before, it was DARK, it was late, it was COLD, and we were lost (my vision is rotten in the night, too). They kept telling us to walk, but I kept imagining the walk being through the savannahs, and having to dodge giraffes, LOL. We finally took the WDW bus, and had another communication issue with the driver, and it was just lousy.
DH took the initiative to help management help the people that hadn't communicated fully. He was listened to, helped in other ways, and felt that he had assisted people at the resort.
Sorry I'm going on and on, but I've been somewhat in your shoes with runs inconveniencing me, I've been in your shoes with bad communication at AKL, and I also know that I felt bad for the backed up drivers waiting for the 10-miler people to clear the roads last October. Empathy all around, and I want you to do something that will help them AND make you feel better.