While I agree with the need for more cliques so we can play them against each other, the Dynatoi option specifically mentions the powerful houses and how we'd be granting them more power by loosening restrictions, offering protections and exempting them from certain taxes.
Yes, we might set the Notables against each other... By enabling them to eliminate their rivals without our intervention. Yes, this might divide them... for a while.
Rather than restructuring things to be based on influence, this could lead to direct force being more relevant.
Eroding Imperial authority doesn't give us candy. It takes away some of our stick, forcing us to rely on candy more even if the need for intervention would decrease.
Would they spread the culture of the court? They might, if they are friendly/loyal to the Emperor. Otherwise they might seek to spread the culture of their dynasty.
Using the Doukas and Dalassenos as a buffer against the rest of the nobility by elevating them above their peers and trying to play them against each other could work though. But that carries its own risks.
Prestige and status are the raison d'etre of nobility. No matter the time or place this has held true.
As such, so long as the imperial court is The center of culture, the most prestigious and glorious place. Then the nobility all over the empire would be doing thier damn best to be role models of the courtly culture.
You can see this with spread of Norman, later burgundian and finally French courtly culture across Europe.
As for the powers being given the nobility, this makes them get more buck for effort from their lands. This basically ties them to the land to some extent, and ensures that a healthy chunk of that new found power is spent within said lands. And as said before, so long as tolls, dues and fees are crown only, we are not losing anything of value.
In fact, we are giving the nobility more provincial options and tying them closer to us. For if we keep them nice and fat on privilege, they will fight tooth and nail against anyone who is disinclined to keep them as such (foreign invaders, rival claimants,.. Etc)
As for keeping then in line, there's plenty of ways, for example: a focus on courtly splendour is very effective at indirectly defanging and declawing the nobility. If it's wealth and power is spent on splendour and attempts at impressing the court, they aient spending it at fighting you. And it ensures rapid cultural spread and homogenisation, with a heap of innovations across the board courtesy of Patronage on steroids.
Or simply increasing the layers of nobility to such an extent that it becomes meaningless.
Or developing the crown fief to such an extent that it alone can keep the vassals in check.
Or dividing up the vassals into ever smaller chunks.
Or propping up the church.
Or establishing urban nobility and using it to dilute the landed one.
Or establish dérogeance such that they are powerless in the areas that truly matter.
All this deals with it effectively if indirectly.