Long ass explanation incoming, Red = social, casual, propvper wannabes. Blue = Leftouts, solos, tryhards, common blade and soul gold sense peeps.

First, do not worry. The faction system is pretty bullet proof and does not really allow a disparity in faction numbers, not in the early game stages following official release.

Whenever a side begins to have more players in it, the faction becomes locked and players must join the other one or wait until some do and the faction they wanted at first becomes available again. I'm speculating it's about 300 players, could be a bit less or more or it could even be a % of the total player base. So the factions are always having around the same amount of players.

As of why there's only guild ads about the red faction: Most clans being formed as the beta and release go on are mostly focusing on the social and will to PvP aspects, which is essentially a part of the red/liberty psychological aspects of human personality. Hence why they pick the red faction.

On the other hand, people associating their guild with the blue faction usually tend to be more prepared, have experience and are simply moving their already existing guild over Blade and Soul. Being experienced in MMOs or in Blade and Soul means they know the red faction bladeandsoulgolds.net player base will not cater their PvP needs and they would see themselves getting wrecked at end-game stages against their fellow productive and skilled blue clans.