In real life, novel mutations are more often bad than good, because the status quo is tightly selected for being reasonable close to optimal.
The same ought to apply to the kind of psychic or supernatural mutations featured in comic book series like the X-Men and speculative fiction works like the TV series "Heroes." But, we rarely seek the dark sides.
One more negative than not psychic mutation might be "reverse mind reading." Instead of being able to read someone's mind, everyone else would be able to know exactly what someone with "reverse mind reading" is thinking.
One might be able to use it in a useful or positive fashion, but I've never seen it portrayed for good or ill.