You're advocating taking someone with a Chad Pennington arm. While there's a chance Barkley's arm strength can get a little stronger, a Chad Pennington isn't going to suddenly morph into John Elway. Think of the quarterbacks that have won championships the last decade or so- Roethlisberger, Rodgers, Brees, Brady, Eli, Peyton, Flacco. Even those who had arm strength concerns coming out of school had significantly better arm strength than Barkley does now. You could say the same for the rest of the top QBs in the league now (Kaep, Luck, etc).
At the same time you're lamenting "missing out" on a guy who doesn't currently have the physical tools to be a franchise quarterback and seems to have little chance of ever having them, you're condemning the Manuel choice based on what you perceive as his inabilities to go through progressions and to process information quickly. It seems like these things can be improved through repetition (experience) and proper NFL coaching. And by ALL accounts Manuel has the necessary intelligence and work ethic to make those improvements. What remains to be seen is whether we have the coaching, but based on their decision to draft a quarterback with the necessary upside at the expense of familiarity (Nassib), I'm feeling better about our coaches all the time.