Because some people need a good, solid reason to attend church...
This is an article from NPR about churches that are serving beer to attract people to church. This topic is similar to the previous Museum of Idolatry post, (the "tattoo church"): sometimes it looks pretty desperate when churches try so hard to be "relevant."
This is not a post against the responsible consumption of alcohol; we have the freedom in Christ to drink (but not to engage in drunkenness). This is about the worship service becoming much, much less than a worship service. When a church adds beer (or anything else) to attract new people, it's really hard for the central focus of our faith to remain so. But there are some notable efforts being made to use the craft-brew phenomena as a way to start a dialogue with non-believers. For example, here's a very interesting group called "The Bible and Beer Consortium" that holds meetings apart from the worship service to discuss the Christian faith. Here's another group called "What Would Jesus Brew?" And here's a good, short article addressing these "beer/church" issues and the NPR article; and here's one more.
There's a difference between a gathering to exchange ideas, listen to speakers and socialize, and an actual worship service. When churches remove all of the sacred elements from the worship service in the name of attracting new people, they end up hurting the very people they are called to serve.
Ultimately, it isn't a good idea to depend on beer (or any other worldly, cultural thing) to bring people closer to God-we've been given Word and Sacrament by God Himself. Praise be to God!