Where is the "never before seen content"?

[Nezerius]

Last time I played, most everything worth pursuing was locked to at least a daily schedule at the shortest - things like world quests and dungeon bonuses (such as they were). Some of the reputation grinds did allow for completing dungeons tied to them, so there was that...but I don't recall those taking long (most were the second highest rep level by the time you finished questing) so the life of that as a motivator for content was short.

Early Legion had the Artifact Power grind, a grind that was so ridiculous that it even made people quit, simply because they felt like they didn't have time to do anything else on their main/alt. It was also pretty time-consuming to clear out all the world quests, especially after they added paragon reputations (post-exalted reputation that would give you a reward cache with every 10k reputation).

I mean, speaking of current content specifically, dungeons here and dungeons there you can farm as much as you want, mythic dungeons there you can so long as you have keystones to do it (so it's limited, but in a different way), Trials here you can. Daily quests here and once a day, World quests (which are just daily quests without requiring you to accept/turn in) there are once a day.

Mythic keystones were hardly limited, even more so after they changed them. Before the change, you could just list your party in the group finder and get someone with a mythic keystone, then hope that it wouldn't get depleted (ie: not clearing the dungeon in time). After the change, keystones simply can't deplete anymore, and the one using the keystone simply gets a new one after the run, which would either be upgraded if the party cleared it fast enough, or downgraded by 1 if the party did not (or did not complete it at all).
Emissary quests are more like the daily quests of WoW, while the world quests themselves pop up throughout the day. If you do a bunch of world quests in the morning, you can expect to have a bunch of world quests respawn in the evening.

Are you sure you're not thinking of an older time in WoW (when grinding reps and currency for gear was less restrictive/less based on daily tasks)?

I'd hardly call Legion's grinds more restrictive than previous expansion, considering players had free reign on how much AP they wanted to grind, the titanforging giving any content the possibility of dropping an upgrade, as well as any content done by the player adding to the "bad luck protection" of obtaining any of the legendary items.