In regards to combat and engame. I only partially agree with the op's post.
I agree that the game should be more flexible in terms of party building and party size.
Ex: I would like to be able to do content with a group of 4 experienced members, or if that isn't possible I'd take 6 instead.
The same could be applied to dungeons intended for 8m. Bring in more players we choose to, maybe even to show the fight to someone new or when clearing when 8m is not possible at that point.
About scripted boss fights, I do agree that they can turn dull after awhile, but at the same time a random fight could be unfair.
So why can't we have a bit of both?
Some fights that are scripted and some randomized fights? Or even a mix that involves scripted "key" sequences in a battle and lighter randomized sequences?
Why not even go beyond the "standard" MMO conventions and make a fight that's not just about players reacting to the opponent but t hat also involves the opponent reacting to players? Perhaps even trying to trick the player.
I believe that a mix between scripted and randomized would be ideal as it would give the player a sense of near-AI.
That being said, I don't mind certain death mechanics. But I believe those should be limited since they create an unfriendly environment for those involved when someone fails to meet the mechanics.
One such example is the orbs colliding in Ultima Hard Mode. Everyone needs to help in order to avoid a wipe, but if a single person fails, the party wipes. Everyone will be frustrated and the overall sentiment towards that person will be negative. This is the kind of thing I believe we should re-think.
I think we should be aiming instead for something like: if a person fails, another good player can intervene and save the party.
The doors in Diabolos for example. You can have the party decide who marks what and who opens what before the fight, and they can all help if they're organized. OR you can have a single player that knows the fight do the doors alone.
While it's a mechanics heavy fight, and while it's a fight with certain death boss skills, it's a battle where one good player can help a group of not so good players succeed.
In regards to bossfight mechanics I would like to also point something out.
Fights like Titan Extreme can be difficult for the wrong reasons. The Titan mechanics are fairly easy to understand, but reacting to them under 150+ms is NOT. I often find myself getting hit by a Weight of the Land when I've moved outside it's area of effect long before it hits, yet the game refuses to detect that I've moved out, this becomes even worse (or so I was told) if you're playing on a console due to an added delay. This needs to be fixed.
The fight becomes frustrating not because people "fail" at doing their job, but because the system will not detect their position correctly so there's nothing else you can do to progress within such a fight since you're at the mercy of lag and the server.
Finally, about combat I would like to conclude with the following. I don't think anyone is asking for "easier" content, I think everyone still wants a challenge. But we want FUN above all else.
Challenges and Fun aren't mutually exclusive. We can have both, but the fights need to be smartly designed.
We want a challenge, we want fun, and we want to feel like we're fighting an epic boss not playing against mechanics and lag.
As far as fun is concerned, I think that this game needs to go a bit beyond just combat. There needs to be more interesting things to do than just battling bosses.
While the basis for non-combat activities is set and probably to a greater detail than in other standard themepark MMOs it just doesn't go to enough depth and there's just not all that much to do.
Housing and decoration were first good steps but we need more. Where's the chocobo racing? Where are more fun minigames?
Why not add a degree of exploration and random puzzle and trap disarming in dungeons? (while a dungeon usually involves combat, these activities go beyond "bosses" and "trash").