Why is everyone slagging swansea off before the new season?

they deserved to go up last season and many pundits agree that they played the best football in the championship but everyone is being ignorant calling them a small welsh club. People are also saying they won't fill their stadium of 20,000 but they have sold 16,000 season tickets for next season. i am sick of people knocking them when they have never seen them play.