Sort of. You're saying undeserved championship challenges that are successful don't have the same weight as someone grinding their way through the rankings and besting the champ, and then defending the title.
I agree that the latter is more impressive, but I disagree that there are many non champ fighters in other weightclasses who could simply move weightclasses and take the belt. If that was true, we'd see it happen.
The times where something like that has happened, have been times where a current and/or dominant champ moves to another weightclass. In these cases, as in gsps case, these fighters have earned their shots via dominance in their original weightclass. Replace "fighting your way up the rankings" with "dominate a different weightclass" as justification for the title shot, which is totally fair.
You want an example of a bullshit title fight - Hendo bisping 2.