Sure, I have only six or seven neighbours, instead of 24 (in which case I'd be completely landlocked, and I really like my Dock benefits, so it's not as big a loss, really), but most of them put up decent trades. Plus, we want our Island to grow, anyway.
Yes but when it was all one big island I often traded for a lot of one item (Glass maybe) because other people I could see on the other side of me needed it, but could not see it. I found there was much more trading going on.
But that would be when you're in the middle, I spent most of my BM career on the outside of the mainland (Building DDD tends to lead to getting nuked), so forming an island didn't cause much of a stress. Plus, it depends on who you're around. I find that I rarely need to trade anything to Ramul (though I did form my own island out of inactives prior to getting real players involved...who are real nice to trade with for base items) though for refined objects, my trading mates are great.