I have an idea to encourage trading.
At the end of each season, Avid can reward players who have the best trading percentages during that season (after say 100 successful trades, for example). I bet the people complaining about difficulty in making trades are the ones trying to ice skate uphill. Some players consistently make horrible offers or reject sensible offers because there's no feeling of "making a kill."
You can also reward players who cumulatively were most generous on the trade meter that season. Seasonal point can be awarded for green and yellow trades that favored the other player.
The prize could be coins, card pack, special avatars, card holders, backgrounds, etc. People who have giant hoards of card need incentives. Having a special card back that designates you as "a decent person" in league play would provide this incentive to people.
We all know how to manipulate the trade meter. You're not being clever. The philosophy of capitalism says that the market will figure it out if there's an incentive.