I wish I could personally. It would save a lot of people from a whole lot of pain and stress. It could even save many people's lives. Then again, I see what you mean about it adding character. Hardships tend to do that.
I see my addiction(s) as being part of what defines me. However, there are certain "incidents" which I'd definitely want to eradicate from my past, but overall, no, I think I'd be a different person today if it wasn't for the path I've taken, and I prefer to own that than to feel ashamed of it. But it's a tough question, and I might say something completely different if you asked me on another day.....
In all honesty, there are sometimes I wish I could go back in time and control myself from using drugs. I realise the number of times I have wasted and the fact I can't get back that time. But at other times I'm grateful for where I am today. I have come to realise that things could have been much worse than it is right now.