I was and still am a big fan of Roger's. The guy just had charisma and an awesome fighting style. The highlight of his UFC run for me was that famous scene where, (I can't remember who) but someone had his back but he was on his knees, and Roger was using the jumbo screens in the arena to see the guy's head and elbow him. It was awesome!
Also, when that youtube clip surfaced of Roger beating the big dude up outside a night club because the guy hit some girl, it was hard not to rally behind the guy.
As far as his downward spiral. I don't think it has anything to do with the LW division being weaker than once thought, I think personally think Roger gave up a little bit when things went the way they did with the UFC. He probably also thought in these smaller organizations, he was going to mow through the competition, that obviously didn't happen.
Just my theory though.