Huh. How'd they end up becoming Barbary pirates, then?
First, you'd notice I precised "safe for raiding" (without talking about the maritime fishing tradition in Maghrib). "Decentralized" naval raids (as in lead, financed by individuals, in a word privateers) are a wholly different thing than a more important navy, organized by and for political intent (such as using them strategically),
The last was clearly less important to the point of unexistance : Marinids were the exemple of a
north african continental power.
Now, if you allow me, your question doesn't make a great deal of sense : we were talking of post-Almohad Morroco, meaning from the XIIIth century, when Barbary Pirates (as in the mix of north Africa, European, and Ottoman models and cultures) exist only really since the late XVth, and not in Morroco.
It would be as asking why medieval Scotland wasn't a naval power when they end up becoming the British Royal Navy, huh?
It's confusing two entities (Barbary Coast/Morroco), two different centuries, state navy and piracy navy, that probably shouldn't.
Not that North Africa didn't knew piracy before 1480's of course : but it was more from modern Tunisia than Merinid Morocco that had a different setting.
"In Morroco, since the marinid decline to the end of XVth century, naval activity never were more than sporadic privateer raids on Spain or other countries, and freeing of Muslims or Moriscos from Spain".
As for the relationship between Arabs and specifically Maghribian Arabo-Berbers and the sea, it could be compared to the relationship Romans had, maybe more violent. Before the XIIth century, and at the relative exception of Byzantines (when the latter were threatened), Arabo-Islamic entities never had real competitors, no need for a real political focus on naval matters (for instance, Balearic Islands, while technically relevant from Cordoba, were basically a Mediterranean Tortuga obeying to themselves first).
It was temperated by the naval tradition of the people they conquered (Syrians, Africans, Greeks), but never made it in the cultural or political matters : before the Ottomans, I can't really think of a achieved Arabo-Islamic thalassocracy.
I think that the Christian hegemon since the XIVth century (Catalan privateers efficiently replacing former Islamic piracy in West and Eastern mediterranea) probably helped to strengthen these feelings by rationalizing the loss of maritime dominance ("Meh, we never wanted it in first place").
Before the Ottoman arrival, that was decisive into making North African coast (at the exception of Morroco, that wasn't in their sphere of influence) the famed Barbary Coast, partially by opposing two maritime powers (Spain and Ottomans) in real naval confrontation (no longer half-pirate/Half-merchant fleet, but two political entities forming war fleets at this only end) in order to forbid as much as possible the presence of each other in western Mediterranean basin, partially to cover the economical needs of the Turks (by slave hunting, as Arabs did up to the Xth century, or Catalans up to the XVth).
You did have organized piracy in Morroco as well, but not before the fall of Marinids and the establishment of Saadi (educated in Turkish courts) that had actual maritime projects (as in, settling in the Americas). Entities as Salé Republic didn't existed before (and represented a foreign and distinct body inside Morroco anyway).
I hope it seems less confuse, now?