Perfectly aware that I'm going to get a backlash for this, and most answers will be signed with a hint of Jackass, I'm genuinely curious.
Why is BJ thought to be such an imposing force. One of the biggest arguments people make when someone says Anderson Silva has four losses on his record so he can't be the best p4p, yet BJ has 4 losses. He's also inconsistent, yet another fighter that everyone says "We'll see which BJ shows up". And he felt he needed to retreat to 155 to be champion rather than toughing it out in the division he clearly wants to be in.
So... what's the big deal with this guy? Seriously?
Let it be known, I don't BJ but this is a combination of what I have read on boards and seen.
Really, its a combination of things. It all started when he entered the Octagon and Joe Rogan ran down the now infamous "facts" black belt in BJJ in like four years, mind you his family is loaded and he could devote all his time to training. He won the Munidals as mentioned before. He comes to the UFC and runs over the LW division winning against guys like Din Thomas and Carol Uno; KOing Uno in record time. Then he takes what at the time was considered a great LW champ to a decision in Pulver, his first loss I might point out. Its here that he is forced to leave the UFC b/c he wanted to fight Gomi, but it would have been in a rival company at the time and Zuffa, like today, didn't allow that. Therefore, he pooled his resources and family money to creat Rumble on the Rock, perhaps you've heard of it. Where he got his dream match with Gomi and won. He then came back to the UFC and fought for the WW title against then dominate champion Matt Hughes and won a fight was considered the underdog. However, was stripped as he wanted to fight in K-1
I get a little shaky here but I think after that win he decided like a crazy person he wanted to fight at WW, MW, and LHW. He did so against guys like Duane Ludwig(w), Rodrigo Gracie(w), Lyoto Machida(l), and Renzo Gracie(w).
Finally, we are in the modern BJ era, he lost a tough fight again GSP and only the title shot for two reasons. First, GSP was injured, he hurt his knee in training and also, because Hughes wanted to avenge
his loss. Which he did but most BJ fans are quick to point out he broke a damn rib in the middle of the fight and continued on. Shortly there after he dropped to LW to settle a score with Pulver which he did in devasting fashion choking him out in the second round. And then went on to win the LW title, the title that alluded him a six years ago. And has since schooled Sherk and could very well being looking to avenge his loss to GSP and possibly Hughes as well. These are both money matches and hardcore fans want to see them.