Ta-Nehisi Coates and Jonathan Chait expanded on something we've discussed at length here. The Republicans are using the Teleprompter meme as a way to paint arguably the most intelligent and well-spoken presidents in modern history as a mumbling doofus.
Here's why. First, it's Southern Strategy politics. They're telegraphing to their white base that black people are stupids and shouldn't hold the office. Second, they're attacking the president's primary strength: his intelligence and oratorical skills. Third, it's payback for eight years of Bushisms.
Of course none of it holds up because everyone uses Teleprompters, from news anchors to sportscasters to cable news talkers to presidents, and, more importantly, there's a considerable record of the president speaking extemporaneously and doing so with thoughtfulness and insight, qualities that our previous president lacked completely. Coates also pointed to this video as further evidence: