I think we tend to oversee the fact that Bobby learned the bidness tactics from the master (his daddy). He was given the "3 B´s" because Jock and J.R. were probably too lazy to spend their time traveling and bribing people all over Texas (and other parts of US too, I'd say). Bobby was young, good-looking and a bit naive, which might be used on his own behalf. Besides, I'm sure that Jock and "Junior" preferred to be alone at Ewing Oil to wheel and deal...
Once Bobby married "that Barnes woman", she clearly influenced him to go work to the office instead of "gallivanting around", and let´s be honest, she made a better man of him without annulling his personality. 5 years after that, Jock is deeaaaad! And his will puts him on a dangerous place: Jock had to be thinking that Bobby really HAD TO refresh his old habits and what he taught him to ensure he might run the company successfully on his own, if and when that happens. It´s old-fashioned upbringing...
Bribing someone was a lesser evil (not that I think it's correct) but all that Bobby (and also Ray and even Donna) thought, was that giving the company back to J.R. would be a tragedy for the whole family (as later proved with the B.D. Calhoun incident...). If Bobby hadn't done all that, he'd been labeled as the stupidest guy on this side of Mississippi...
But great writing as was that season´s under the cynical eye of David Paulsen, elevated the show´s drama to another category, almost biblical. Cain vs. Abel bring the 4 horsemen of the Apocalypse, almost the end of the world as we knew it on "Dallas", with a touch of Dante´s "Inferno" in Southfork´s fire. Can you get more genius in a primetime soap?