Petec, as I understand it, the state monopoly on alcohol (System Bolaget) obliges people selling drinks with alcohol above a certain level to have a minimum price that cannot be less than their selling price. I also think that, less than 3.5%, the tariff is a lot lower, so beer is cheaper.
That said, Folköl (the 3.5% and below stuff, as opposed to Lättöl (lower than that – see Pripps Blå…)) is really good. Depending on where you are in the country you can get a lot of really nice local beers. Howsyourdad has one of the best breweries (Jämtlands) up near him and some of the new ones near me (Uppsala) are really good. Tempel Brygghus is one that specialises in sour beers and makes some great beers.