Meh, it would just be awkward at this point, and frankly a little insulting, but I'd be ok with it for their sake. I won't pretend that bulling at my younger years did not affect my life negatively, but I also don't particularly place the blame on bullies. They are an external factor I could have responded with appropriately. I blame myself that I did not handle it appropriately so it did not become a pattern, and this knowledge motivated me to improve myself.
The rest is irrelevant, and the bullies themselves different people now, with no real connection to me. Blaming them would be rationalizing my own weakness to stand up to the challenge at the time. An apology would really be for the benefit of the bully's sense of guilt, not really a consolation or atonement.
Ofcourse, I wont claim that all bullied people had opportunities to handle the situation, so I am sure in some cases it's appropriate. But I do think that it's far more productive for most bulling cases for people to use the experience as a lesson, instead of simply being angry at their aggressors. To be clear, I am not victim blaming here, I am just saying that anger and blaming is unproductive.