Whatever you may think of Reagan personally or politically, serving as the governor of California most certainly counts as a respectable stepping stone to the presidency. It counts for ANY governor of California. Whether the American people elevate him or her higher than that is, of course, at their discretion.

You might be able to say that Reagan had insufficent credentials or qualifications prior to being California's governor. That argument was indeed made by his opponent in the 1966 gubernatorial election. The voters of California didn't buy it.