A few points...

First... I agree with what you're saying....

part of it is lighting... Like that dwarven skyrim city... Its like Cassieopiea but darker... as it should be... There is way too much unnatural light in this game.... The only light in Cass should be from the glowing fungii and that's it.... Caves are the same way
The black shroud? is under a canopy of trees that completely block out the sun yet its bright as the dickens... even at night. how much light are we really getting from those little stone candle things?
It may seem nitpicky.... or even inconsequential... but lighting goes a very long way to setting the mood

Also... the tech demo... and even the Ul'dah opening scene just have more lively NPCs going about their business and THAT also leads to a more alive world... But thats been talked about a lot in the "Eorzea more dynamic and alive" thread

Also... specifically with the bridge... could it have been because the game was so rushed that it came out so much simpler than the extravagant artwork? Like the landscape designers just ran out of time?

Another point... Is the world too pristine?
Everything looks so new and untouched...

Lastly... there is an aesthetic choice of more realistic environments as opposed to over the top fantasy scenery....
Most of what we see in game could really exist in the world... that seems odd for an FF title... there is nothing that you see and say "WOW... thats unrealistic but AWESOME"