I think they might not be factoring the past winners for the same reason they didn't factor Sandra. No one forgets Tina won, but it was so long ago and the game is so evolved now. And no one remembers Aras winning
For Hayden, I'm wondering how many of the other players are BB fans, because his win was one of the more deserving ones in BB history, and they should take into account that he has the muscles, but also the social skills to win this thing. Maybe having a goofy annoying girlfriend is a good thing for his threat factor
re laying it on thick with Vytas/Aras - I'd blame the producers/editors - this is their Big Emotional Journey story for the season, perhaps more so with Brad failing to get further and be the Big Alpha Star. Aras/Vytas are going along with it because they know it makes good tv and they likely also think it's not a bad thing to promote with the other players either, so they seem less of a threat - which seems to be working for the most part so far (only Tyson is targeting one of them - so far no one else has). When they switched tribes and Vytas started to tell his story again, it felt almost scripted.