Just because players were once great at playing the game doesn't mean they understand it. It's why very few players who played at the very highest level make great managers.
BBC, ITV, BT etc get the 'names' in to appeal to the Sky 4 armchair fans. Sky, especially Soccer Saturday, targets them along with the 'lad culture' demographic that still watch Soccer AM (if that's still going), and switch over to watch the nonsensical ramblings of idiots before the games.
If they were to watch a pundit that really knew the game and could put across eloquently the meaning of decisions the likes of Pep makes, they'd spontaneously combust.