Its routinely quite easy to pick up at least 1 rare and about 300 gold. Just always focus on the bottom most column matches you can (unless you can see a 5 match) since it cause stuf to fall down, and the best way to get stuff is cause as big as a cascade as possible and force rare generation from that 'heroic effort' bonus.
Once you've got a few rare icons, focus on moving them near one another with matches, rather than the gold you might get, which is paltry in comparison to what you might get from selling an item, usually.
"If the world's a stage, and the people actors, then who the **** has my script?"
I like the loot game, but I do know what you are talking about and it is a bug. It happens when you match 4 or 5 of a kind in one direction and at least 3 in another direction. If the green or blue item is going to spawn in the intersection of those two matches, it spawns but is immediately destroyed by the other match. I didn't think it was that big a deal, usually it happens due to cascade luck and not the player's intention.
Just as a counterpoint though, I've gotten 5 green, 5 blue, and 400+ gold in a single chest. I rarely come out of the game with less than 3 green and 2 blue per chest. There is a lot of luck yes, but there is also a good bit of strategy which minimizes the need for luck. And if you think you're "missing out" I wouldn't worry, the items you get are almost never good enough to equip. The shops always have better items in my experience.