Each to his own! In this case, however, the sole purpose of the plugin is to widen the stereo image - not to add something to the sound. The idea is that a trumpet is still a trumpet, it just takes up more space in the stereo field. This plugin can "almost" do that, unlike a typical chorus effect that is supposed to turn one trumpet into 10 trumpets or a typical echo, which changes the musical meaning of your music (melodies don't always lend themselves to being echoed).
As a sound-engineer I've also found that music, since its made up of complex sound, benefits from sounding simpler, when played through a mono source. In other words, music benefits from less chorus, less reverb, when played in mono. It makes everything clearer and easier for the listener. I use phase-cancellation as a tool to improve the sound. To accomodate people who listen in "mono like" enviroments while giving other people the satisfaction of fat stereo.
But would the affected voice (or whatever) not become quieter when played from the mono source?