The problem with all of those things:
1. They're level capped. Never mind the general player base's hatred of level caps (there are exceptions, but in the minority), but there are also many cases where jobs just plain don't come into their own until higher levels. Relative job balance, bad as it is, is better at 75 than it is at 20. Not to mention people tend to be very rusty at playing the level 20 version of their job.
2. They require a reasonably sizable group of people. Furthermore they require some semblance of organization and cooperation and execution of strategy. Except...
3. This one's more of a catch 22, but *because* the events are fairly universally disliked, getting an entire group of people who already know and work well with each other (at, moreover, the level cap) is nigh on impossible. Which in turn means that if you're looking to do these events, chances are very high you're doing them in pickups. And that's pretty much a guarantee that problem #2 will come into play. Which in turn just makes people dislike the events more, which makes problem #3 worse, and so on and so forth.
Garrison, EF, et al. might actually be fixable simply by making them uncapped (and a suitable but not unreasonable challenge for 75s). Or with optional caps akin to Assault. But forced level caps, an annoying and usually *not* fun experience (for the above reasons), and crappy rewards... of course nobody does them.
I've done Eco-Warrior exactly three times, once per country. Each was a miserable experience that made me swear I'd never do that version again. (Well, the Sandy/Ordelles one was merely *unpleasant*.) The actual process itself isn't so bad... it's the headache from all the people not working together remotely well.
