just ties you up with mandatorys until they strip you. hamed never was unified but beat the wba/ibf/wbo/wbc i think during his reign but was striped or his opponent was stripped and he ended up never more than 2 belts at any one time from memory. fighters you beat for the tiles much more important. for example macranelli just beat the 300th ranked cruiserweight in his first defense , giving some example of what belts are worth in todays market. 25 years ago bobby gunn would not have been accepted as a challenger to southern area belt title challenge.
ok, and yes, if someone is just fighting at 1 weight class he ends up fighting smaller opponents that are moving up in weight classes or same sized boxers and IMO thats not exactly EXCEPTIONAL and exciting.
trouble i also have with fighters who say like mayweather move up through the weightclasses is they pick and chose very carefully which champ they go after. and then move on before the diffucult awkward opponents have to be faced. for example mayweather will never face someone like rival champ travis simms, or welterweight paul williams. baldomir was taylor made to outbox and judah was small than himself y leanord/hearns/odlh etc etc all went the same way by and large with a couple of exceptions avoiding the most diffuclt opponents as they moved up. IMO it dimieshes there acheivements even if the record books say otherwise.
That's why I rate becoming WBA, WBC and IBF championhigher than picking up just the Ring belt or another title. Mayweather and Hatton would have had to fight at 140 for either of them to be the real champ rather than Hatton beating Zoo then picking Maussa, Collazo and Urango while Mayweather picked Judah and Baldomir (wasn't Hatton desperate to fight Baldomir too at one point?). Hopefully we'll get Hatton-Mayweather later this year to sort it all out.