There wasn't a moment were it became recognized, it was a process. In the late 90s, with Hamed and Oscar de la Hoya. In the early 00s, with Wlad and Brewster. Others that helped: Calzaghe, Margarito.
For what sake? These WBC/WBA/IBF were just another straps. Neither Ottke nor Bayer were something special like e.g. Eubank. Joe could feel he has nothing to prove with these guys. And we know he was avsolutely right.
Name me as many WBU top fighters as I named you WBO and yes the WBU is a major title. WBC, IBF, WBA has no more of a claim than WBO as being a real title. They all became recognised titles much the same way the WBO did, when top fighters decided to fight for it. IE: guys like Calzaghe doing 19 defenses on it. I could easily say that the fact Lacy finally decided to challenge for a real title in WBO proved he wasnt worthy enough a champion as obviously the WBO champ who defended the crown for 19 defenses had proven it so.
He would likely have been robbed blind if he went to Germany to fight Ottke, by the ref or judges or both, and Ottke sure as hell wasnt going to fight anywhere else.
The very reason the top guys didn't go looking for Calzaghe is that he didn't have a legit title. Eventually he realised he'd have to challenge them and he has since beaten Kessler and Lacy and won all three titles. That's great but it doesn't validate his reign as WBO champ it simply means he should have fought for the real titles earlier. You may say "yeah but why did he keep the WBO title once he won the real titles?". Well I ask you, what would you do if you didn't want to undermine your 10 or so years as "world champion"? Drop the title or keep it? Your claim that the WBO became a recognised title is false. It is not recognised by the hall of fame, the ring and most fans outside the UK. I don't know how any one can call it a recognised title.