Communion is a big thing; although there are only a few accounts of it each going for a few verses, a whole lot more can be gleaned from it when studied in the context of the whole Bible. There are many lessons to be learned, and a huge amount of doctrine and teaching is represented, upon which people are encourage to meditate and give thanks for. I think the focussing on Jesus' words and actions is encouraged when Jesus gives the instruction to remember Him. I believe that this doesn't only refer to His impending death, resurrection and ascension, but also to the entire ministry He'd done up to that point; all the miracles and teachings and what they mean. Mark 8 shows nicely why remembering what God has said done in the past is important for understanding what God is saying now. In fact Jesus rebuked the disciples for not getting this right. Part of communion also involves looking toward the 2nd coming. There's also the consideration of what the new covenant is, what it means to be a part of it, and the "celebrating God through singing" afterward. In some ways it's to feel a part of something, which is important, but I believe that it goes much, much deeper than that.
Further to all that is the actual bread and the wine (“fruit of the vine”.) One must consider what each of those represent; the bread for the body and the wine for the blood. Doing a study on the bread, body, wine and blood is quite extensive (as there are well over 1000 verses to take into account,) but it's quite interesting.
For example; communion happened during Passover, in which there was no leaven (which represents sin) in the house, nor in the bread. Jesus took the (unleavened) bread and said "this is my body." This indicates that His body was without sin. Consider 1 Cor 5, in which we're instructed to be a new lump without leaven; (that is, without sin, like Christ.) Through Christ all things are made new. Communion reminds us that it is through Jesus' body that we are able to fulfil God's instruction. Consider 1 Pet 2:24, in which it says that Christ bore our sins on his BODY, on the tree (cursed is anyone who hangs on a tree,) that we being dead to sins should live unto righteousness. The bread reminds us that Christ took our sins on His body (in fact, all sins going back to Adam, represented by the crown of thorns,) and in doing so has freed us from sin, not so that we can keep sinning that grace may abound, but to live unto righteousness. God wants us to live a righteous life, and it's through Jesus' body that we can do this. That's just a brief couple of things that the bread brings to mind for me. There's a lot more including sanctification, deliverance from sin, bodily healing, obedience, the relationship between bread and feasts and the relationship between bread and the Word that are also relevant. The bottom line is that there is quite a lot of meaning and application in the bread and body.
Consider the cup, representing blood. Blood is needed for atonement. Blood (death) is the price that is paid for sin. It is the price that has been paid for redemption (Jesus buying people back from whom people used to belong to.) The blood (of Jesus) gives life (eternal) to the body (the church); without blood there is no life; an appendage starved of blood with wither and die. The body is the vehicle through which the body (both individually and of Christ) can accomplish things on earth. Jesus' blood is what gives life to individuals and the church, and enables them to function. There's also deliverance from death, forgiveness of sin, the relationship between blood, and wine to feasts (and their fulfilment,) the seal of the new covenant, and the tree of life. Further to all that, I see a relationship between communion and Daniel 8:14, regarding the cleansing of the sanctuary.
All that is only a very brief overview of some things that the bread and wine represent, I'm certain that I've nowhere near covered all of it, but there's some insight as to "why bread? Why wine and why is it spiritually important?"
