Although encryption is one the weakest part of the wireless environment, it is not worse than fixed land network. There is another weak point, which is much worse in wireless network than fixed network, that's the authentication part.

In a wireless network, it is much easier for a third party to break into an ongoing session or authentication process, and steal data, or even initiate the authentication process by pretending to be an authorized user.

One of the problem is that, normally the first part of the authentication process is not encrypted until later, and in a wireless environment, it is easier for intruders to quickly intercept data.