Much of your gripes are a combination of development choices along with player influence. Let's take dungeons for example. If you were to create a four-man dungeon that has three paths to the final boss, and each path represents a level of difficulty (easy, normal, hard). The path you take will also determine the HP, attack power, and defense of the final boss along with the mechanics he throws out at you. Which path do you think over a prolonged course of time would be the path that is ran the most?
Now this isn't an example to prove that players will choose the path of least resistance. What it actually is meant to portray is which paths they are wasting time developing since they are ran the fewest. With this in mind, a big reason why we don't have more dungeons is because players who don't care to run them are in the majority. I would not be surprised going forward if the amount of dungeons continues to go down to every other patch, to eventually 1 or 2 per expansion and then possibly only solo/trust supported instances remain. 4-man content in general is phasing out, though it will always be there for new players. For veterans though, there are fewer things most of them could enjoy less than running yet another dungeon.
Everything else you mentioned can all be considered old content. It's been around as long as the game has been. Since then other content has been added: PoTD, HoH, Masked Carnival, Unreal trials, Eureka, Diadem, Bozja are all time consuming content that you have not mentioned, and this content would not exist if they insisted on sticking to allocating resources towards dungeons, job quests, leviquests, etc. Granted a lot of time still goes into designing high-end duties and alliance raids, but this is very popular content that players very much look forward to doing, and have a high replay factor as well.
Reworks are just fine if it is for the better. As newer jobs are released, so are the mechanics that drive those jobs and the others become outdated. If you've ever tossed something on your UI while leveling an alt and thought, "Hey! This is a sweet addition I should have thought of sooner. I am also going to add this to my main job." then you should understand the desire to rework jobs a great deal. Some jobs NEED a rework though. There are aspects about them that make zero sense and the job, and enjoyment of that job suffers. Just ask long time ASTs that finally hung up their globe this expansion. MNKs and the other healers are also all on the verge of pursuing different paths.
MMO change over time. You have to adapt to those changes, or bye bye sub.