Considering Lucas Till has not only portrayed a comic book hero in multiple X-Men movies (for those unfamiliar, he portrayed Havok), but for a few years he was also MacGyver! It is both his time as part of the X-Men universe and his MacGyver moments that make him a perfect fit for Booster Gold because he has the hero experience under his belt with each of these roles. Of course, it also helps that he is a blonde!
He has that something extra that makes him seem like he could handle being both a showboat and also a man who has had to deal with tragedy in his life. Till is the kind of versatile actor who can also give us a hero trying to overcome his past.
Lucas Till is also 32 years old, which means he is old enough to bring maturity to the role, while also being young enough to grow with the character for years to come. It just seems like he has the charisma and gravitas it takes to portray a hero using his knowledge of the future in a way that he might come to regret. He has already shown a lot of these characteristics over the five years that he portrayed the titular character of MacGyver, so it really just makes sense for us to deck him out in the signature black and gold costume and have him bring that to Booster Gold.
Of course, it also helps that X-Men isn’t his only time in a superhero-style role. All of this is to say that if there is an actor who can step into the DC Universe and bring life to a hero that some may not be familiar with and make the role his own, Lucas Till would be that man.