Boo to Kurrawong! Sure, it's true that in our reality, horses don't think quite so much. But this is Middle-Earth, and a horse of legendary bloodline... it's OK for it to have a little more sentience than an ordinary horse might!
I found this story poignant, and it has a sort of sweet innocence. And I can just imagine the cruelty that might be visited on the poor animals with the misfortune to serve Mordor... urrgh.