I have 3 otos and two large pieces of driftwood. I don't think the otos eat or snack on the driftwood, but I know for sure that they like to hide out under it during the day. I occasionally see them during the day, but generally I have to look in their favorite hiding spots in and under the driftwood when I'm counting noses.
When doing my research on them I read that they were one of the few Plecos that don't need driftwood.
So, although I planned on putting driftwood in my tank- I didn't do it immediately.
As soon as I put the driftwood in the tank she was a changed fish. She was way more active- way more social and within a week of me getting wood for her she was full of eggs.
I don't have Ottos- but being related to Plecos I know if I did have them, I'd certainly make sure I gave 'em some wood. My Bulldog was not supposed to require wood... BUT- man oh man- she's a completely different fish since I put my wood in the tank.
Oto's do not require driftwood. It definately won't bother anything if they have it though as it will add to their bio diet. They won't munch the wood but will graze on any goodies that would grow on it.