Ok, why do aedra find empkres so important?
U got akatosh blessing allessia with being dragonborn because shes head of an empire.
Akatosh gives allessia the amulet of kings saying rulers over all men will get to get akatosh blessing by wearing the amulet if their ruler over all people and in doinb so perform the rites and get akatosh blessing.
Remen was a dragonborn.
Tiber Septim was a dragonborn who eventually afyer a dragonbreak became a "God".
The septim rulers because they were rulers over an empire got to wear the amulet and in doing so perform the rituals and get the blessing of akatosh.
Martin who was heir to the empire and camoran who was heir to the ayleid empire both worn the amulet of kings at the time an empire had no ruler bit could be considered it having 2 at the same gime fighting for who would be imcharge of it.
Martin eventually takes on the aspect of akatosh to beat back mehrunes.

Like to point out that allessia, remen, and Tiber built their empire from the ground up and were dragonborn whereas medes empire didnt have a dragonborn but also their empire was basically taking over the septim empire. They didnt build it from the ground up and strangly wasnt dragonborn.

What exactly is akatosh deal with empires? What so important about empires and creating and maintaining them that akatosh gives kts blessing for it?

Empires must be appealing to Aedra as they have an Anuic bias; that is, they are related to stasis and order. Empires reinforce that status quo among the different races of TES.

Yet the founding of these Empires are almost entirely padomaic, as are the ends to them. Each causes a massive and radical bout of chaos and change.

In my opinion, everything goes back to Alessia. Akatosh wouldn't give a damn about empires if he hadn't made a deal with one specific ruler and give his blessing to one specific government change-over. Note that there was already an empire in Tamriel during Alessia's time: the First Empire, based in Skyrim and extending into High Rock and Morrowind. Akatosh didn't care at all about that empire (part of that was likely because Nords wouldn't give the Time Dragon the time of day, let alone worship, but still). Akatosh took an interest in Alessia, though, and because of that anyone he considered Alessia's heir--regardless of blood relation--would be given his blessing. It just so happens that the empires that rose due to "Alessia's heirs" were the only empires that we recognize from that time onward, at least once the War of Succession tore Skyrim apart. Other Tamrielic powers such as the Aldmeri Dominion aren't considered "empires" for various reasons.

In my mind, the question isn't why Akatosh is so interested in Cyrodiilic empires--the answer is "because he was interested in Alessia." The question becomes, "Why was Akatosh so interested in Alessia?" Note that Alessia's only quoted prayers are directed to Kyne, through Mara. In my view, Akatosh is most interested in Alessia because of Pelinal (the "Akatosh and Shezarr are the same" theory, specifically) and because Alessia's victory was directly responsible for the foundation of the Eight Divines pantheon. If he was at all interested in helping Alessia in his own right prior to her victory, the only reason I can see for it is because of the Ayleids' practice of dealing with Daedra.