That Obama was Oratory Incarnate was the first big lie of his myth, but unfortunately not the last.
I've heard platitudes and empty phrases, delivered mechanically, on-stage, fumbling and vagueness impromptu. Real orators are articulate and cogent both on and off teleprompter.
I think the problem is that people compare him to Bush II and no one else. Since GW BUsh mangled a few words now and then, anyone that can speak clearly without doing that is some sort of amazing speaker. Personally, fancy talk never impressed me much. I'd much prefer good content and substance. I didn't think GW was a great speaker, but I didn't think he was near as bad as people liked to say either. The opposite is my opinion with Obama.
It was some years ago, but I remember hearing a congressman speak once that got up and spoke off the cuff to a to a group of a couple thousand at a meeting. He was a little tentative at first, but once he found his audience, he had everyone laughing and listening to every word. I don't remember what he said (20 years ago), but he was entertaining. IMO, that was good public speaking skills (not counting content). The stuff Obama does is just reading. He does it better than I could, but speaking better than an engineer is nothing to brag about.