It's nothing to do with Southern bias, yet more Altrincham paranoia.. they're simply the most attractive ties to put on tele.
AFC Wimbledon have risen from the ashes of having their club killed and made it to the first round for the first time ever, and drawn league opposition, it's a 'fairytale'. H&W became a household name last season, renowned for their cup run and defeating league opposition - they have that chance again, so they could be picked for tv.
Luton v Altrincham won't capture the imagination of your average armchair bum, it's just a team who have had points deducted in a home banker against an average part-time non league team. That's looking at it realistically, nothing to do with agenda's, vendetta's or Southern bias etc etc..