This all realy depends on your neighbourhood, in mine there are only 2 persons trading, and seeing i am one of them we made an agreement to trade any goods of an era that we hold a deposit off 1on1 ... now it turns out that we only have 1 good that the other doesn't have. So while it is great for us to trade marble for lumber, and jewels for ebony. That is all the trade i can manage to do, this means i currently run 6 goods in my city (one of which i hold a deposit, which i sometimes switch out for the other deposit, aka. wine/marble). The other ones are all 'slow' goods production units, and by the looks of it my next expansion will need to be occupied with another 4x4 goods production unit if i want to progress at a somewhat reasonable pace, given i can squeeze out enough population to actually sustain it, this will bring total to 7 goods. This does mean though that i lack production buildings for supplies (which tends to become quite obvious from me waiting to get supplies to progress) and also shows in regards to my military options, i will need to make real choices soon if i want to be able to keep up in military strength...
So global or even server trade would realy help, you can concentrate on the goods that you have a deposit off, and maybe one or two buildings that are a bit more rare ... instead of actually HAVING to build all goods production buildings because there is absolutely no other way to attain the goods.
It would also help if you could trade for gold, supply and diamonds on this server/global market, making it easier to attain the stuff you need, while focussing production on the things you already have ...