I don't dislike Ritchie (although his form is frustrating me atm), and I wouldn't sell him in January, but I just don't really think he has the pace for the top flight long term.
He's a winger who can't dribble with the ball and doesn't stretch teams with his pace off it, that's a major problem in this league in this day and age IMO. Even if he had the best crossing and shooting technique in the world (he doesn't, although he's not bad) it would still be a problem.
There's a long line of one-paced midfield and wide players who have starred in the Championship over the years, racking up big numbers of goals and assists. I've said on here before that above average technical ability goes a long way in that league. Peter Wittingham having a 20 goal season springs to mind as a notable example.