I realize that I may have no room to discuss with you as you play on a higher difficulty setting then me.
Just because someone plays on a higher difficulty doesn't mean you can't comment on strategy. Don't feel like your opinion doesn't count just because you are still learning.
For what it is worth, on larger maps I also have the experience of trade not being worth it. The most I ever got from one route on a large map was 240/turn... and that route was 8 sectors long and was up for 6 years straight. At the same time, I had close to 50k in income from population and taxes, so the extra 2k I was getting from trade did little more than fund my spies.
Trade is still useful as a diplomatic tool, especially as you try to add up factors to get a race to "close" so you can get an alliance. May only be a few extra diplomacy points, but I find it matters.
On smaller maps trade is absolutely vital to your economy, and to overcoming the early game "crash" many people experience. Add in that from the tech you get extra diplomacy, the econ capital, AND can buff relations - and it becomes a vital part of overall strategy. On smaller maps.
I think the problem could be fixed if the distance of the route had a much greater effect on the value of the route. (For math nerds:) Currently, it appears to be a linear progression that is quite low. Make it an exponential progression, or a cumulative linear progression - and I think trade could become an important part of income on larger maps, assuming that on those larger maps you sent your traders very far away.
An interesting discussion though.