An excellent critique, and one that is entirely in line with your namesake's thinking.
To respond to the point you proffered about the social background of my examples - only Camillus can really be counted as neither a member of the Ordo Equester or the patriciate, as none of his ancestors held distinguished posts - the others are either from the most respected families (Cornelii Scipiones, Licinii Luculli) or distinguished families of equestrian origin (Domitii, Pompeii). Now while it is true that the aristocracy was not the sole class motivated by the obsession with dignitas, they and the richer members of the Ordo Equester were the only people with sufficient power and influence (or even distinguished ancestors) to follow in the cursus. However, you are entirely correct in pointing out that I was rather narrow in my premise.
I was not advocating that the only path to glory was to butcher your way to a triumph, but as the topic was indeed about whether the glory of a triumph was a main motivating factor in the composition of the Imperium Romanorum, I thought it necessary to distinguish the sole glory of the triumph from the pursuit of glory in which a triumph was merely a piece (and probably not even the most important one).
The points about the greater accomplishments of Roman magistrates in peacetime is also well-founded, but after the fall of Hannibal, what real threat was there to the existance of Roman dominion for a prospective "Scipio" to oppose? Mithridates? He only really threatened the Roman hold on the provinces of Asia and Greece - and even then he only survived as long as he did because Sulla was first too preoccupied with the Cinnans in Italy to pursue the war to its end; and then Lucullus was racked by mutiny fomented by P. Clodius.
So in conclusion, I agree heartily with your points about the Roman greatness in peacetime administration, but maintain my position that the triumph was merely a symptom of a greater sickness, perhaps one that eventually caused the fall of the Republic when the resources of the men competing on the cursus became too great - the hunt for glory.
Edit - The negotiations between Sertorius, the Cilician pirates, and Mithridates might have formed a coalition capable of threatening, at the least, the Sullan hold on Rome; however, the assassination of Sertorius and the successive appointments of Lucullus and Pompey to the war against Mithridates and (in Pompey's case, the pirates) effectively ended any outside force capable of facing down Sullan Rome. So while there might have been an outside force for a young "Africanus" to be pitted against, fate had other avenues in mind.
I still rather wish Sertorius' vision for a Romanized Hispania had come to fruition.