Done upwards of 800 level 6 chests. Of course, you get the gold, 30K and about 5K off of guardians. I loot the mana orbs, pardons, alacrity scrolls, pinks, skeleton keys and essences to keep and sell or use. I turn in the shields, the refinements, and the sashes, for points. The rest of the junk I leave in the chest because it will only total 200 or so points in total and it is too much effort to carry it all back as my backpack will overfill if I loot the lot. I also take a quick peek to see if there are any 100% elemental resist weapons to save. The useless minor artifacts are also turned in for points.
For me the excitement is receiving a level 7 map and ultimately snagging another coffin piece. It is also a pleasure to sell 100 lots of pardons for 100M or more per lot.
More to the point about RNG and lockpicking, on level 6 chests I have taken up to 20 tries to open the chests, have had up to 6 gas explosions on occasion. I average about 2 to 5 attempts to open each chest and have not noticed a recent change in the odds.