A few of these aren't so bad... "Can't Help Falling in Love" is just a cover in a particular musical style. Not sure what else is supposed to be done there, it's not like UB40 wrote the actual song and they didn't cover it badly within the boundaries of their own style. A few of the others are just corny soft-rock music, but not exceptionally bad in the scheme of corny soft rock.
"Ebony & Ivory" is an actually terrible song. I think "We Are the World" was just as bad for mostly the same reasons. There's something transcendently bad about compiling a bunch of legendary talent, making a huge marketing deal out of the world-changing song they are about to unleash, and having it turn out to be sappy sentimental garbage which isn't even catchy let alone appealing.