I believe that Expansionistic is the worst, because it depends of a LOT of conditions:
No it doesn't.
You can use it to great effect on continents also.
I'm confused by this. You can just set the barbarians to be sedenatary, without any effect to the map.
I have never used it on a huge map, I have never used it on a Large map. I play Standard sized maps, and it is a
fantastic trait.
4- No mountains (except for the Incas)
That is stupid. Mountains are a help to scouts, as if you see one out in the open, you can move towards it and see more of the surrounding terrain.
You are never going to get 3 whole columns of mountains on any maps anyways, besides the fact that it is only going to slow you down for a turn or so. It is insignificant.
5- No more expansionistc civs
Emm... You are still going to be able to get a hell of alot of huts. The AI starts off with loads of warriors and whatever anyways, so it doesnt matter if they are expansionist or not.
It endures only in the Ancient Age
Well if you use it properly you can easily be finished by the Medieval age, so that doesn't matter. And you can still explore once you get to the Medieval times anyways. Infact, the only thing which doesn't endure to the medieval ages is getting techs from huts, you can still get anything else you usually would.
All of your points are ********, there is no chance that you know how to use this trait properly.
Expansionist is the best trait for Pangaea/Continents maps. Ok, it might be slightly circumstancial, but I get a free settler/city every 2nd game. It's more like every 2/3 games.
The only time this trait is not particularly useful is on Archipegalo maps, although it still can be good.
I say seafaring, as I never build a navy, and I don't like starting next to the water.