I find most people who's goal is to WIN don't keep or display plaques where they lost. (Losing = not 1st place). I do it in very select occasions. For example, I have a plaque next to my door from the match I lost by about .1 match points - to remind me that every point counts. I don't keep the majority and I know quite a lot of shooters who feel the same way.
Other than that, frankly, it's no ones business what a competitor does with the plaque they were given. I don't see how it's disrespectful at all - it isn't insulting the match, staff, or competition. It is solely based as a representation of your performance. I bet 99% of us throw the stuff away we get in the sponsor bag when we register for the match too, but I don't see anyone screaming "foul" over that. By that logic, isn't that disrespecting our match sponsors?