We don't have trading mainly because the loot pool is shallow, in respect of items suitable for trade. You wouldn't trade for white/green/blue items. You probably wouldn't trade for legendaries, with the exception of maybe raid and event items (Lantern gear for example). Trading would be limited to a narrow selection of exotics. For example, I never got Gjallarhorn in open play but with the ability to trade for one I could have got one easy. Would have made my life much easier back then.... This would have made RnG largely redundant though. The market would be flooded with thousands of identical, surplus items (Gjallarhorns) and everyone would have everything within a very short space of time. No reason to grind for anything, you'd just buy it. There isn't the depth of loot to make trading a viable part of the game. There never has been. There [i]are[/i] ways to make limited/timebound trading work but even then, would we bother?

There's really not much in this game that isn't easily obtainable.

Because newbies will get all the exotics instead of earning them.

Because most of us, including Bungie, don't want it.

Trading would kind of ruin the game.

Dumb question...that is all.