Vocal music in theory is no more or less trite than instrumental music. It depends what selections they choose.
I am concerned about choices that draw more attention to the singer than to the skater.
Taking the option to use a few lines of vocals in several minutes worth of mostly-instrumental program will likely be the most successful approach.
:agree: Some voices (especially operatic ones) are so powerful that you almost can't help paying more attention to them than to anything else. In the non-opera area an example that comes to mind is Odetta, who had a voice so big, so powerful, and so compelling that she could stop you dead in your tracks. Not saying that any of her songs would make good skating music -- just using her to represent a non-operatic voice that really could distract an audience.
The bottom line is that you'd have to be careful to choose a good performance by someone who's not going to overwhelm the main event -- the skating. Talk about tricky...
Full disclosure: I'm a singer, so I love just about any type of vocal music. As a skating fan, though, am inclined to be a bit skeptical of vocal music/lyrics in competition. OTOH, for exhibitions, fine by me! There are a few wordless vocal pieces that I think could work well for skaters, especially Villa-Lobos' Bachianas Brasileiras No. 5. Will try to come up w/ others & post later.