i was watching an ad for some kind of tv show or something last week (i've been told my mind is a sieve, and this beginning may give you a clue as to why!). anyway, the only bit i remember is a man proposing to his beloved in front of an audience full of people. and it struck me that this wasn't a particularly nice thing to do.
it's something that's pretty hollywood - the hero going down on bended knee in a crowded restaurant, or having his proposal announced at a baseball match as tens of thousands of screaming fans watch on. i'm sure you remember many such similar scenes. and it's always presented as some kind of super romantic thing.
but really, i see it more as a kind of harassment. ok not in 100% of cases, but it seems to me that the main purpose of the public proposal is to put pressure on the other person to say yes, or to make it that much more difficult for her to say no due to the general embarassment it would cause for herself and for the person who was asking.
i guess it wouldn't be as bad if you were absolutely sure your partner was going to say yes - but then how can you be absolutely, completely, totally sure? people can change their minds for any number of reasons, in the space of hours or even minutes. what they thought was a wonderful idea in for months on end might suddenly not seem such a good idea, and suddenly they're not interested in marriage any more.
maybe i'm just an arch-cynic who doesn't have a romantic bone left in her body. but a public proposal does not seem like a good idea to me.