I acknowledge your right to your opinion and I mean you no disrespect by this comment:
Opinions like this may eventually bring the Civilization franchise to ruin.
No, it will take player like you away (Or not, because you will probably like the new system once it release), and player like me much closer.
Having game more complicated does not make them better. The slider for culture, tech and espionnage were all very Obscure aspect of the CIV 4 gameplay wich only a few people were able to enjoy (I certainly did not).
Hapiness over the whole empire is just a new way of representing the stability of your empire as a whole, in reality, having one unhappy city at the border could very well make the management of the rest of the empire more complicated for the ruler as he needs to put more energy and ressource (Manpower and financial) to balance everything. So that's there way of representing this into the game.
And I mean... Puppet cities are a new feature, I don't understand why it's ''bad'' not being able to assimilate every city you conquer when your empire is not stable enough. It make sense and seems fun.
PLUS, having to much city from conquest was VERY annoying in civ 4 since you were always asked to build new building for city you didn't even cared about. Overall, I think it's great new gameplay feature that will make conquest a lot more fun.