To act like all rookie quarterbacks have the same potential for success is flat out Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!). There are indicators and NFL scouts, personnel guys, and television analysts pretty universally aren't high on Geno's. I don't know if he will succeed or not, but I (and them) would put the odds on not. The investment of a first round pick and #1 overall pick isn't worth his odds of success and could be terribly detrimental to a team.
Alex Smith made big plays in the playoffs, had the highest QBR when he was injured last year, has won a pretty decent amount of regular season games the past 2 years, and lets you keep a first round pick. Geno Smith at #1 is pure desperation and hoping he is RG3, after he showed over and over again last year he was not.