I think there may be some real merit to your idea but I think the bigger picture is that they wanted both Tanking and Healing to be more accessible to new players. The aggro changes definitely made Tanking far more simple and pushing Healers toward healing with increased damage output across the game and simpler DPS options definitely cements the "healing" aspect of the role. Scholar is boring but much much easier to grasp and crossing from Astro to Scholar to White Mage is simpler than ever as they homogenized the skill sets so much. This seems to tell me they were more concerned with adding to the small number of Tanks and Healers without considering that the ease of play might not have been the issue but the fact that Healing and Tanking just weren't as fun or flashy as most DPS jobs.