the general assumption is that it's easier to complain than praise.
A certain high street store certainly likes to put that into principle. They have no email contact details on their website. If I wanted to contact them to praise the way a manager dealt with my complaint it's either a stamp, or an 0845 phone call.
There seems to be a growing trend of trying to deter contact via email ... is this because all companies want you to "friend" them on Farcebark ? Possibly a bad tactic, since it publicises your bad reviews as well as good.