This is subjective. I find leveling my other jobs in PotD to be very boring and brainless. On the other hand, I enjoy leveling in Eureka, for multiple reasons. I'm not saying that this is the pinnacle of fun by any stretch, but grinding Fates in N.Thal, getting Atmas, doing books, gathering light, going A1S again an again, doing years old content, and so on... isn't what I'd call "fun" either. I'm just aware that I'm playing a mainstream WoW-like MMORPG, which helps not raising my standards too much. If Iwanted true novelty and innovation, I wouldn't be playing FFXIV. So, I'd say that people's standards and expectations are part of the issue.

I just hit level 13 out of 20. So, I'm still in the leveling process, not even close to being max level, and I already have the equivalent of 3k crystals. This is enough to have a complete armor set of +2. Or almost 3 Anemos pieces. Or two +2 weapons and some letfovers. Or... you get the idea.
Once level 20, I think that Eureka will become my favourite place to go to gear alt-jobs. Plus, I like quite a lot of the AF3 gear, so, that's a nice bonus.
Call them trash if you want, but they won't hesitate in one-shotting you faster than God Kefka if you are careless. Besides, almost all the "trash mobs" have different kind of attacks. Some cleave, some have ranged AoE, some petrify you, some apply a potent poison, some jump all over the place... Even if it's small, you have to adapt to them in some way. The terrain also plays a part in this.
Sure, it's still farming trash mobs. But a lot of FFXIV is actually exactly that, would it be dungeons, fates, PotD...
Same as above, all NMs have a different strategy that you have to follow. Especially if you go on higher level Fates. And while people compare them to rank S Hunts, the fact that the trash mobs are so dangerous changes the way you approach the fights quite drastically. Also, you are killing them at a very quick pace, all things considered. When I do some Fate trains, sometimes it only takes 10 minutes between the death of a NM and another. The average seems to be between 15 and 20 minutes though.
Maybe one of the reason why I like fighting them is because I'm a tank.
For you main job? Yeah, surely. For you alt jobs? Eureka is probably one of the best content to gear them right now. Looks good though. Isn't glamour the true endgame anyway?
Although I'd agree that the chests are quite annoying. When you get back to camp with a hundred or two to open, only to know that the fast majority will be trash, you'd wish for the rewards to be better. Or at least useful like Eureka potions, a raise potion, some cristals and whatnot. I blame RNG too. Still no mount and no chocobo barding. Sadness.
If there was no penalty for dying, Eureka wouldn't feel threatening at all.
It's clearly not some mind blowing content and it obviously has been overhyped (I still think that people are somewhat responsible for their own expectations though)...
It sure has its flaws, but saying it's 100% garbage is dishonest.