"but he was reelected, and by a clear majority"
49% to 51% may be enough to win (what you call "clear") but that means HALF of the people that voted didn't want him back. That is not "clear" in my opinion. Technically, you are correct, but I have beef with the electoral system in general, which we don't have to discuss.
"If he won, unmerited on his father's coattails, he wouldn't have gotten reelected."
He didn't win because his father was the president, he won because he embraced conservative values and was given the opportunity to become president because his father was president.  His opportuntiy was because of his father, which lead to him being the candidate, who all republicans then voted for (the first time) because he followed party lines.
His father didn't win him the presidency, but it got him close enough to bullshit enough people into electing him. Had he been born to your father or mine, he wouldn't be in office.
/////ENEMY () WITHIN\\\\\