I personally think that the simplicity of the DPS role in earlier content is okay. Both tanking and healing can be daunting roles for new players, so I think it's fine that there's a low-pressure option to complete the main story with.

I always felt like the job quests should be more instructional. For open world objectives, they often make you use a certain ability that you already have, just to learn another as a reward. Also, I've found a lot of the job quest solo duties would've been easier with the spell I learned afterwards. I feel like the "duty action" would be really helpful here. Make the new ability a duty action, and teach the player how to use it in the solo duty. They could also be more challenging. I think it would be more fun if there was a real chance of failing the duty in ways other than simply not reading the instructions. This would improve player skill without embarrassing the player in a public setting and completely redesigning instanced group content.