I read the pages about him on the wikia and I don't see anything about him betraying Azura or anything. His enemies, the Tribunal, are the only ones that I can find reasons for her to hate. He guarded the tools, as the Nerevar ordered him, and then he lost them to the council who used them(which was against Azura's wishes and was exactly what Dagoth was trying to prevent).

So why did Azura want Dagoth dead?

For the same reason She and the rest disliked the Dwemer (presumably) he was connected to the heart and gaining power from it, and also seemingly trying to make his own "Numidium"

Or maybe she's just a vengeful ***** who wanted everyone involved with killing her plaything dead

Azura wanted to have the Heart removed from the picture (as her revenge on the Tribunal) - and there isn't a way to do that without killing Ur. Though it has been ages since I've played - when was it mentioned she wants him dead? I honestly can't remember.

Because the Sharmat, who both betrayed and did not betray Nerevar, was an obstacle to Azura's revenge on ALMSIVI.

Never mind the big stompy robot he was working on, as well.

1. Heart.

2. ALMSIVI

3. Dagoth's nega-CHIM would be mega-bad.

Maybe.

Self-interest. Dagoth Ur wanted to free the Dunmer from superstitious tradition and false gods and issue in a new era of universal godhood for his followers. That doesn't leave a lot of room for her.

On the other hand, protecting the Dunmer people from a life of mindless servitude to a false prophet and his god-construct, as well as her other children (the Khajiit), who wouldn't fare so well in a Dunmer paradise.

Azura wanted revenge on the Tribunal, and Ur was an obstacle to the unbinding of the Heart of Lorkhan. Also, she wouldn't like Dagoth to success either, the situation would turn even worse that way than when the Tribunal ascended.

Dagoth Ur's plans were to tweak metaphysics in order to create a new god. Azura wouldn't have liked that any more than she liked it when Kagrenac was working with the Heart; recall that she sent the Dunmer to war at Red Mountain for that very reason. However, I am not well versed in what Dagoth Ur actually was, as his entire existence seems wrapped up in metaphor and metaphysical examinations that go well beyond my ability to decipher. All I know is that he was a "dead god who dreamed that he was alive," which confuses more than clarifies, in my opinion. Certainly, though, any success on his part would leave no room for Azura, who (as one of the Good Daedra) was still revered by the Dunmer even after her place had been redefined by ALMSIVI, and who still had some hope of retaking her old place once ALMSIVI was removed.

That said, I don't think Dagoth was necessarily an obstacle to Azura's plot to destroy the Tribunal. Quite the opposite: I believe that Dagoth was her chosen tool. Dagoth's connection to the Heart meant that the only way to destroy him was to remove the Heart from play, which would (coincidentally, of course) remove ALMSIVI from the picture. Dagoth's rise forced the Tribunal to either accept their mortality for the sake of destroying the greater threat, or to be destroyed by Dagoth instead. Obviously Vivec got around that trap, but that clearly wasn't Azura's intention, and the deaths of the other two indicate that she was at least partially successful in her plan.

Dagoth ur represents a conscience, for what he did was loyal before the heart corrupted him. By killing him as the player, you just destroyed the last thread of sanity that you will have and be lost forever trying to find answers to the most mind boggling questions that your mind can create here on the elder scrolls lore forums. Which is precisely what Azura intended.

nega-CHIM?

Dagoth Ur's plan was to unite all the Dunmer with the heart in order to combine them into one consciousness and then he would've used the Akulakhan to destroy everything else, Akulakhan is essentially a Numidium. Once done all the being in Nirn would be one with the heart who is Dagoth Ur and then Dagoth Ur would just need to reach Amanranth since I think he already reached CHIM. At least, that's how I see it.

CHIM is the realization that I AM AND I ARE ALL WE.

Dagoth Ur thought that I AM AND I ARE ALL ME. The opposite of CHIM.

Wouldn't it be "I AM AND WE ARE ALL ME"

The I is still important.

Probably, just the "I AM AND WE ARE ALL ME" just sounds more accurate, maybe it's just me.

For instance the statement "I AM AND I AM ALL ME" could be seen as the person realizes they are themselves, it doesn't necessarily mean all those around said person are them like "I AM AND WE ARE ALL ME" does.

Are you sure it wasn't "ALL YOUR BASE ARE BELONG TO US?"

For people who don't understand the above, CHIM is, blandly, the realization of being in a dream with the rest of creation and having the presence to endure and shape the dream. The flow on, is that all other people are a part of you. Even as you are part of the dream of everyone else.

Dagoth Ur reached the first realization, that the world was a dream, but he thought that all of the dream was his dream, and all of creation was part of him. Basically. It is frequently noted that this is basically the reverse of, or negstive form of, CHIM. For his part, it seemed to have given Ur some powers.
However it is wrong or falsr path, at least according to Vivec, which would lead me to think one couldn't reach Amaranth this way. I don't see why this would be so, so I'd welcome discussion.

The Good Daedra, it seems, have a special connection to Lorkhan, so that could also play a role why Azura didn't want the Heart to be used by anyone.

There's a fan-made document floating around in TIL, I believe, that discusses Dagoth's metaphysics in depth, which was brought to my attention during the Amaranth Hunt because it made a pretty good case for Dagoth being the Amaranth, or at least put forward the evidence in such a way that that was one of the logical conclusions.

I figure it had something to do with the fact that if Dagoth Ur won, he'd force the Dunmer to all bow down to him and to receive the Divine Disease. Not a pretty picture.

It's pretty clear Azura knew about Dagoth Ur beforehand, and even warned about him in the prophecy "The Seven Curses". I think she knew from the beginning that the Tribunal would end up facing a foe that they could not predict, one they could not defeat, and whose downfall could only come in their relinquishing the power of the Heart of Lorkhan. Not a pawn for revenge, I think, but an indicator of a point, that for all their supposed power and good intentions, the Tribunal could not foresee threats like a higher being could, and that their little stunt was doomed from the start to come crashing down in failure, not due to machinations on Azura's part but due to previously unforeseen threats, the Tribunal's own blindness, and the failings that would be their own undoing..

Really, I figure if anyone was actively working to destroy the Tribunal, it wasn't Azura, but Sheogorath. Madness does seem, after all, to be at the heart of the Tribunal's fall.

All this sounds... reasonable. I don't think the forum likes to think about Azura as a reasonable being. We like to bash her. Quit being reasonable and join the rest of us.

To be honest, though, while I don't have a particularly high opinion of Azura, I guess I don't see exactly why she's been turned into the Goddess of Stealing Other People's Credit and the Patron of Posers. That said, I just haven't paid that much attention to her after I figured out the gist of what Boethiah and Mephala did for the Chimer/Dunmer, so I'm probably missing quite a bit.

Can you point me in the direction of this document?

She wanted him dead as a mercy. I'm pretty sure either her or one of the Ashlanders says so in the game, but I can't be bothered to look it up.

http://www.imperial-library.info/content/when-dead-gods-dream (it's actually a forum post by Luagar, not an archived text). It certainly deals with dreaming, which is (in effect) the heart of the Amaranth concept, but it doesn't say anything specifically about Amaranth, unless I missed it when I was briefly looking it over again before posting it here.

Thank you.