"Moroccan Arabic ... differs from Standard Arabic in phonology, lexicon, and syntax ... and is nearly unintelligible to other Arabic speakers..."
"...most uneducated Moroccans do not understand Modern Standard Arabic..."
http://en.wikipedia.org/wiki/Moroccan_Arabic
In most cases, it is more useful to have some French in Morocco (and also Tunisia) than Modern Standard Arabic. MSA is in use in business and public administration, but we find French-speaking people can do business there. Educated people usually speak French fluently, and expect to converse with Europeans in that language.
But Moroccans are remarkable linguists, and if you are there as a tourist, and don't have much or any French, you won't have to go far to find someone who speaks fair English or Spanish.
But if it is just for tourism, then I think learning MSA could be a waste of time. If you do come across someone who speaks little French, you'll usually find they don't speak/understand MSA either.