No, not really. I could care less. If however, the decorations actually did anything in game mechanics, then I would be a fool not to. For example, I can put down tiles and make cute little paths around my habitats, but to do so sacrifices space on islands that we already know have space problems given the number of monsters in the game. Plus if my workers can be doing something productive to improve my game play, I am going to work on that as opposed to do something that makes my island look pretty and nothing more.
Let me suggest something from another game I play, Civilization. In that game roads increase your revenue. Highways which are an upgrade increase it even more. So maybe, just maybe:
- Cobble adjacent to a habitat increases gold production .1%
- Cobble adjacent to a farm increases food production .1%
- Paving adjacent to a habitat increases gold production .2%
- Paving adjacent to a farm increases food production .2%
- Crystal Paving adjacent to a habitat increases gold production .3%
- Crystal Paving adjacent to a farm increases food production .3%
You see where I am going Gold should do more, since it costs more, but adjust the percentages however you want.
Now let's talk flags. I think flags should induce a certain pride in your monsters and would boost a particular element. For example the green flag maybe only boosts nature monsters strength or prime stat by .5% and only if they are adjacent to a habitat. You might want to limit the number of flags and you might want to then add more to make sure all elements are covered. If you really want to open a can worms, add in book flags, but since I think people organize their habitats by type and not by book, book flags might not be a good idea.