Just because it keeps the same elements, doesn't mean it's a bad game.
I've played every production of Tropico and, yes, although it is very similar to every other Tropico made. Arguably, this game hasn't changed all that much from even the first one. But that hardly justifies the poor reviews.
The graphics are amazing, the humor is impeccable, and the detail is immersive. Honestly, I'm not the sort of person who expects or even wants considerable change from every sequel.
If a set of parameters have been found to be successful, stick to them. Improve the graphics as a bare minimum, and make only slight changes to avoid the risk of ruining an otherwise great game.
And this game has achieved just that, providing just enough new elements to justify playing it.