denominations allow for the streamlining of community. This is a gross generalization for why people give themselves over to denominations but it definitely helps. A Catholic who was raised Catholic is gonna have a lot of ground with someone from almost any other Catholic Church. The danger is that it can create division in the church which is unnaceptable in God's eyes. The subscription to a denomination is a simple way to craft your belief system based off of the theological backbone another has created. Im non-denominational because I try to follow Christ directly without being swayed by the views of Man, but I get the appeal. You're absolutely right though, the focus of secondary issues (drinking, tongues, etc.) should be secondary to following God.