Interesting debate - here's my POV:
I was always opposed to marriage for feminist reasons BUT I knew that it was very important to my oh and I already felt a long term commitment to him so when he asked me to marry him (after five years of co-habiting) I agreed (after thinking it over for a little while). It wasn't 'a proposal' - he had forgotten that I was meeting a friend after work, my mobile battery was dead so he couldn't find out where I was, he got worried, and when I got home I was greeted with "Where were you? I was worried! Will you marry me?" (And my instant response was something along the lines of "I TOLD you where I was going, you berk.")
I never had an engagement ring (although, 14 years later, I do have a lovely set of three stacking rings for my right hand, one to mark the birth of each child - much more meaningful IMHO). We were starving artists at the time so had v cheap wedding rings which we replaced a few years later when we had more money.
Our plan for the wedding was to go to Marylebone Registry office followed by a picnic in Regent's Park (bring your own picnic). My parents offered to pay for a wedding that they could invite elderly relatives to so we ended up having something a little more formal than originally planned, although we still eschewed many of the familiar elements of a wedding - no religion, 'giving away', white dress, table plans etc.
I kept my name at first and he kept his but when we decided to have children we wanted everyone to have the same name so we double barrelled. The children are capable of working out what to food they marry. They might follow the Spanish model where everyone is double barrelled and upon marriage the woman keeps her mother's half of the name, the man keeps his father's and the two make a new name - or they might follow their great-grandmother's example - she had a triple-barrelled surname!
I would have been perfectly happy to stay unmarried and just arrange wills etc. The wedding day was nice, but just one day. It did 'feel' different to have made that commitment, but I think I can see both sides of the meta- marry/don't marry discussion.
In your particular situation, Woah, having been the reluctant party, I see two possible explanations: either you haven't made it clear how very important it is to you, or he has a reason not to marry that is strong enough for him not to care about how remaining unmarried makes you feel.
My oh didn't threaten to leave, or cry, or make a legal argument for marriage. He asked me to make a commitment that was vitally important to him and, because I loved him and felt committed to him
already, I felt that his feelings on the matter should take precedence.
Time for a heart-to-heart...