I think a lot of people just don't like the taste. I've made juniper tea before, and it takes a fair amount of branches and berries to get a strong taste.
Randy Mosher has a section in Radical Brewing about Finnish Sahti. He recommends 1 oz of crushed juniper berries at the end of boil. In addition, you boil the mash liquor with juniper branches, and lauter over more juniper branches.
Hops are almost nonexistent in this style, mind. All the spicing in a sahti comes from juniper, with just a touch of hops to help with preservation and to balance slightly.