It doesn’t matter to me if anyone who plays Richard III looks exactly like him. Way too much is made of this as a prerequisite especially when considering the use of prosthetics and special effects. Does it help that Richard Armitage has some resemblance to Richard III? Yes, there’s no question.
As for those who don’t think our guy looks like Richard III, certainly RA doesn’t look like RIII all the time. He has some features that resemble the King, but remember Richard Armitage is a chameleon. It’s one of his greatest assets. After his voice, it is my second most loved aspect of him and watching Sparkhouse for the first time and seeing how differently he played John Standring from John Thornton, Harry Kennedy and Guy of Gisborne made me a life long fan. Yes, I can say that with confidence since I doubt his ability is going to go away. And it would certainly be beneficial in playing Richard III.
Screencap is mine.