Going to answer your question, hopefully it'll help your research. I am not casual by any means, sure I have a job and all that, but I realize I can be pretty hardcore when I want to be, and on average I play about 5 hours a day (which is definitely outside of casual I'd say).

1. Content that has gated me, and for how long:
- The Binding Coil of Bahamut Turn 5, 3 weeks (technically, I was able to enter T5 since 7 weeks or so ago, but I only started to seriously attempt it 3 weeks ago)
- The Navel (Extreme), 4 weeks

2. Why am I stuck there:
- My static has some member issues. Recently, one of our members left due to some real life complications, and we've found a replacement, however he is currently not geared enough to follow the strategy that we use. It will be a few weeks before we can attempt T5 as a static, and until then I believe the rest of us will clear T5 on our own time. Pugging T5 has not helped me progress much either, if anything I feel like I am stagnating.
- I am simply too lazy to do Titan Extreme. My priority at the moment is T5. I also spend more time levelling my alt Warrior and Dragoon than attempting Titan.

3. Am I upset: Maybe for Coil T5, since I have been trying to pug it for 3 weeks now, but with pugs I have not managed to gone beyond Conflagration. The only thing upsetting me is my lack of progress on Turn 5, despite investing hours.

4. Should any changes be made: I think the content is fine as it is.

5. What kind of content would you like added: It differs from individuals, but I would really like more dungeons. I don't think they should be as hard as Pharos Sirius at the moment however.