Paul wrote the following,
“I marvel that you are turning away so soon from Him who called you in the grace of Christ, to a different gospel, which is not another; but there are some who trouble you and want to pervert the gospel of Christ. But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed. As we have said before, so now I say again, if anyone preaches any other gospel to you than what you have received, let him be accursed.” Gal 1:6-9
The Gospel message preached by the Apostles and recorded in the New Testament was and is true and complete, and can be either accepted or rejected. There has never been a need for a "restored" gospel. I do not say this with disdain, as I am sure Joseph Smith was indeed searching for truth and you who are Mormons are sincere in your belief as I am in mine, but only one can be right. And since Joseph Smith seems to have done the exact thing Paul warned against, adding to a Gospel that was already complete and declared finished by Jesus Christ and receiving new information form an angel, wouldn't the New Testament account be more reliable than extra-biblical books added in the 1800's? The Gospel didn't need to be restored just preached.