Delicious eisbock is expensive to produce on a large scale and must be aged. The unwillingness of larger breweries to produce it gives it a mystique, and it makes a great addition to any brewer's beer cellar.
Barrel-aged beers are wonderful, but barrels are also expensive, time-consuming, and take up a lot of space. With the wide array of oak alternatives available, they are also unnecessary. Explore the alternatives to barrels.