I failed Copperbell Mines HM, (low on time) but going by your rule I shouldn't even bothered with it since then..., I don't know, I feel like exploring new locations and facing new content is reason more than enough to do it, even if is slightly harder.
And that's fine if you want to! It's your job to get the experiences you want out of the game to keep it fun for you.
But since SE is effectively giving me a choice between running an extra, annoyingly difficult dungeon compared to the others "just for fun", I'm going to say "no" because I don't actually find that idea fun (at least the second time on, or with randoms I'll never see again). It's the same with PvP: I don't find it fun and never will so I will ignore it just like this dungeon, even with PvP actually having specific rewards for participating. And I'll say the same thing for that: if others like it, great! But leave me out of it because do not want.
All I am missing is "the experience" of one random 4 man dungeon that is absolutely going to lose every bit of its novelty in short order. There's plenty of others I can run on "autopilot" in a fair more efficient fashion and finish much more quickly/reliably to get back to the content I find much more enjoyable. I am busting my butt on things like Titan EX and T5 that are 'fun" and actually give me something for the extra trouble. I
know SE is capable of properly rewarding players for increased difficulty, and I also know that they are capable of understanding why so many people will say "no" when that reward just isn't there. Experiences are great, but I don't want SE to be lax with the compensation either.
Just read the past ~4 pages in this thread, and I'm feeling a bit intimidated by the talk on EX primals and party expectations. Is it really difficult to pull together a group to clear or is it just that people don't like doing EX with inexperienced members and will stick to farming runs with people that have cleared it multiple times over? That really wasn't the kind of attitude I expected to see at endgame.
It's usually not an attitude you see. The problem about Titan EX is twofold: 1) he knocks you out of the fight completely most of the time if you mess up, so rezzing for additional practice is impossible. Moreover, because he knocks you out of the fight, you end up not being able to even
see what's going on and how people react to it. Patterns/placement/positioning ect. And 2) at this point in the game, you need everyone alive to properly tank, heal, and DPS him down in time since there's a soft enrage mechanic or two built in to him to prevent a prolonged encounter. You don't actually need to perform perfectly (I've eaten a bomb or two and shrugged it off) but it's tighter than just about anything else, and that's a lot to expect from DF or people new to the fight. He literally starts being able to knock you off (effectively a 1shot with no chance of recovery) every 20-30 seconds towards the end for several minutes, and that's assuming you can keep the normal damage/healing in check (which is also no joke). So the problem of not having "experience compounds itself because of anyone else messes up more than you, you don't even get to the parts you actually need practice on.
That being said, I fully intend to help folks and pass down my knowledge as I learn the fight so others can do so in turn (just like I do with Garuda EX). Titan HM was a breaker of spirits and this is notably harder in all aspects.