1. Dragoon has a much much easier time against monk where there are disconnect. Primals are prime example of this.
2. Your experience is not wrong. However comparing a job where there are many spots that they can mess up positional to a job where you only have 2 skills to hit positional, the one with more positional should have less penalty per error. Is that wrong? A dragoon and a monk that cannot do their job effectively will be bottom of the barrel easily. Monks do not have the easier time here.
3. A monk does not do that much damage over a dragoon of equal gear and skill. Maybe you just lack one of the two compared to your monk counterpart. You're only i95 with unfinished Animus.
4. Dragoons need a buff to their magic defense yes. That does not make them glass cannon however. You're not required to take damage most of the time unless it's unavoidable damage. You're not tank. There's no reason whatsoever that you should do incredible damage. Now go complain about Summoners. They have one of the best mdef, best or second best single target damage, get boost with foe's requiem and very good small group aoe damage.
5. As for complexity of the optimal rotation, it's just optimal. It does not mean you will always be able to use it. It's a rotation you use on a dummy to test your maximum. How much efficiency you can bring to a fight depends on how well you adapt to the fight. At the end of the day, dragoon is still a priority-system job.