I don't think it's a bad idea, but depends on the person I guess. Like, I had some friends back in the day that I could never relate to now, and to be honest we never had that much in common to begin with. However, my best friend from childhood I still talk to on a semi-regular basis. I haven't actually seen them in over 10 years, but we still talk because we always shared so much in common we were almost like the same person, and it seems that time isn't going to change that.
There might be a short awkwardness in first reuniting, but everything in life is kind of awkward at first. Also depends on if you really want someone else in your life right now. Sometimes you don't, or they might end up being a bit more invasive than what you'd prefer. Just some things you might have to consider when it comes to having friends at this point.