8 is a lot, I would get a second opinion if you haven't already.
Most dentists try to avoid pulling so many teeth for braces because they've found that pulling two premolars usually gets the same results (the standard used to be all of your wisdom teeth). I see your wisdom teeth probably need to get removed in general but the additional 4 afterwards is a bit unusual. I guess looking at the X-ray they're pretty compacted as is so there's not that much room left to move them around. I'd still consider double checking though. Once they're pulled that's it, you can't get them back.