Francis Pieper wrote a 3 volume set entitled "Christian Dogmatics" between 1917 and 1924.  Although titled "Christian Dogmatics" his work is presents thoroughly Lutheran position.  Pieper served as the 4th president of the Lutheran Church Missouri Synod from 1899-1911.  Although his work has aged it is well preserved and is still the fodder of systematics classes at our seminaries.

In volume 3 Pieper asks whether Christians are free to join or not to join a congregation.  Pieper offers 3 reasons why Christians ought seriously to seek membership in a local congregation. 

If you were asked, "Why should people attend church?" What would be your answer?  I think Pieper's reasons will be similar to yours, however his ordering of his reasons, which I would submit is quite intentional, reflects a proper Lutheran Law-Gospel approach, but notes that the law is good.  It is not the intention of the gospel to overthrow, get rid of, obliterate the law.

Why Christians ought to go to church reason 1: "Because it is the will and order of God that Christians...not merely read God's Word privately, but... hear God's Word publicly preached..." The premiere reason for going to church-- God tells us to!  Imagine that!

Why Christians ought to go to church reason 2: "Becuase it is the duty not only of the individual Christian, but also fo the congregation to admonish and reprove the sinning brother, the whole congregation is enjoined ot exercist Christian discipline."  The second reason notes that the church is that place where Christian admonition, Christian reproving, and Christian discipline, for the sake of not losing people to licentiousness, takes place.

Why Christians ought to go the church reason 3: "Because in particular the celebration fo the Sacrament of the Altar is not merely a church custom, but a divine order for the exercise of brotherly communion."  Reason number 3 may have been your reason number 1-- the church is that place where we receive God's gifts to maintain our brotherly communion. 

Pieper's ordering does not mean that he is stingy with grace and a hard roller with the law.  I think Pieper is on to something here that we may have let loose of: the church, a local congregation, to properly portray the work and words of God among her members, needs to diligently exercise, and not simply talk about, both law and gospel.  Ours is to remain faithful to God's revealed order for people and their lives, and indeed the state of their conscience, which will determine whether they hear words of and experience law or gospel.