How do you figure Vonleh has a "slim chance" of becoming Jermaine? And no, overpriced role players are at the bottom of the list for a reason. Which champion do you know said "I know! Let's pay 8M a year for a role player. That'll put us over the top!" Not even JJ Redick or Kyle Korver or Tony Allen (much better "role players" than Ariza) got 8M/yr, and they didn't put their teams over the top. Who did the Heat or Spurs overpay to be a role player? No one. They got a bunch of MLE, BAE and vet min contracts while (in the Spurs' case) they picked up young players with upside to develop that others had passed on. Danny Green, Kawhi Leonard, Patty Mills all played "role player" parts on some really good teams. Mario Chalmers and Norris Cole were young guys who played a role, and role players like Battier and Anderson and RayRay didn't make 8M/yr.
So yeah, recent history shows that winning teams have more Noah Vonleh types contributing (rookie contracts, upside, maybe not their first team) than Trevor Ariza types (veteran role players, 8M+/yr, downside of career). If we don't have 2-3 go-to players, it doesn't matter if we have role players or not. If we do, we don't need to waste cash (or the opportunity of getting those go-to players) on expensive role players.