It's not a matter of "how much". It comes down to whether I enjoy the content and whether I feel like I'm revisiting somewhere and enjoying nostalgia or if I'm just doing the same thing over again. The latter has never really happened in WoW.
All of the raids you listed I enjoyed. Like the vast majority of the playerbase I never raided Naxx so the fact it was the same raid again meant nothing to me. Similarly I never raided Ony, and in any case that was one boss and it was mostly for nostalgia purposes. ZA/ZG were excellent dungeons (at least until the VP structure made me run them 1000 times), my only dislike is that they removed the old ZG mounts in the process of rehashing. Deadmines was fantastic, SFK was also really good - the only downside being that story changes meant it was no longer a dungeon full of Worgen. SoO reuses some rooms but I mean, it's the Siege of Orgrimmar - duh it reuses Orgrimmar.
Scenarios are a great way of making content without Bliz having to spend dungeon/raid resources to do it, and they're super convenient, some of them are fun too. Also can be good from a lore/storytelling perspective. I wish there were more story scenarios in fact. And anyway, most of the MoP scenarios use terrain that was clearly made specifically for the purpose of being used in the scenarios.
DS was kind of a mixed bag, IMO it was too soon after Wrath to be revisiting Dragonrest. I liked going back to the Eye, pity I hated Hagara so much. Would've preferred to see a bit less of that and more new rooms. I didn't mind the Ultraxion fight though, Dragonrest suited that. The last three fights were good as well.
TLDR: I enjoy almost all of this content so I don't care that it's "rehashed" - at least in terms of the actual rooms/terrain.
Nothing about BWD was rehashed. You might as well say MGT rehashed TK because it had K-T in it.
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You're missing out, ZA is great.
DS isn't half as bad as people make out either.