I think 7 was to be expected. For me, from 4 onwards the game has been moving in this direction. I think less and less effort has been made from 4 onwards to hide the fact that you are playing a board game, not leading an empire. I think the AI has gotten worse since 4, not better. I think less effort has been made to add personality to the game and to add personality to your opponents. Effort seems to have been focussed on initial prettiness and accessibility.
I enjoyed both 5 and 6, i clocked up a few thousand hours in both but could feel the way the game was heading -especially with 6.
Yet sales of the game kept improving each time, 5 sold more than 4 eventually and 6 was the biggest success of all. So i can see why the developers made the decisions they did with 7.