I've known some people who had the misfortune of going to Texas public schools, and there it was mandatory to recite both the pledge of allegiance AND a pledge to Texas. WTF.
To answer the question, no, the pledge should not be mandatory, nor should it be mandatory to recite it in English. I mean, if someone somewhere wants to recite it in a different language, what does it matter? They should be happy that anyone wants to recite it at all.