#4 His promos aren't nearly as bad as fans think
Roman Reigns still gets blasted for "not being able to cut promos" because on instances such as the infamous "Daffy Duck" fiasco, which occurred two or three years ago.
But Reigns is proof that less is more, and when the material is right and the dialogue is clear and concise, he's certainly not one of the worst talkers in WWE. In fact, you could argue that there are plenty of stars who have had significant pushes despite being unable to cut main-event level promos.
Do stars like Jeff Hardy, Finn Balor, Brock Lesnar, Randy Orton or Bayley cut better promos than Reigns? No, they don't. Even Internet darlings like Cesaro, Matt Hardy (when he isn't "Broken") and Seth Rollins aren't exactly all-time great microphone workers, but since they aren't despised by WWE's most vocal fans, their weaknesses as talkers are often overlooked.
Reigns will not go down as one of the best mic workers in WWE history, but if the main goal of a promo is to get the fans to pay attention and buy into what he's saying, then Reigns is clearly doing his job and doing it well.
See the promo above, where Reigns says one sentence in about 10 minutes but has the crowd eating out of the palm of his hand the entire time.