It would deffo take away a lot of the excitement from the game. The crowd plays such a big part in sports and it is the crowd that allow for those spine-chilling exciting moments. For example, Agueroooooooo wouldn't be as entertaining without that huge roar from the audience.
There's nothing better than the roar of the crowd a a game, but I'm really getting desperate to watch live sports again and I would love to see something, even if it's without fans.