Anyways, you're contradicting yourself. You say they choose to do it like that in front of thousands of people because they feel it's romantic. At the same time they interrupt whatever the audience was doing and focus their attention on you to witness your major event. The whole attention part is intertwined with proposing in front of a mass. You can not magically cut it out.
Attention will always be part of it, regardless of your reasons to do so.