I like building scarcity, it makes specialization important. One of the reasons why Civ 4 and 5 are so good is that they emphasize strategic choice for which buildings to build in your cities. It's ineffecient to build every building everywhere, instead you build the money making ones in good money making cities, and the production increasing ones in your big army producing cities. In Divine Wind, it should work the same way. You may only get to the final building of one type in each province now. You'll have a core set of provinces dedicated to pumping out lots of strong land units, while you focus on building trade buildings in provinces with good trade goods, and so on.
Provincial specialization should make you think about how you place buildings, should make the really good buildings more scarce (let's face it, EU3 could use something to give it more challenge, it's piss easy right now), should give smaller countries who can afford to build more buildings per province a leg up against bigger countries, and will make provinces more interesting. Right now every province is the same, pretty much, just with different tax values. Now you'll have industrial provinces, bureaucratic centers, etc. It gives the game more personality.
Just my two cents.