Players could level all crafts to the original cap in FFXI too, and then later were allowed to select one craft to master to the raised cap. This was fine in that game because crafts were just a side task, not an actual class. Crafts are supposed to be playable classes in FFXIV. Some players, myself included, actually enjoy leveling crafting jobs as a class. If I were suddenly unable to continue leveling my classes, I would lose interest in playing. I do enjoy my DoW as well, but I spend a large chunk of my time crafting because I enjoy it.

If someone suddenly told you that you could not level any other DoW/DoM classes beyond 50, you had to pick just 1, I think you might lose interest in playing as well. (The "you" in this case refers to everyone in general, not any particular person in this thread).

I would like to be able to continue to level any class from any category to the level cap. However I would also be in favor of specializations for each craft and access to those specialties could have restrictions (similar to what was done in WoW as one example). Only crafters with that specialty could craft recipes in that category. Each crafting branch would would have similar choices, and each player could specialize in only 1 specialty per craft.