Currently my opinion is that the accessory system - a random chance of pulling any one of 300+ items is a too random, let alone acquiring an item in the colour you need or that rare item you are after. Years ago I played a popular CCG that had a system of ranking cards as common, uncommon and rare and the ratio of these in a pack was always the same - now I'm not suggesting a guarantee of rare items or anything but how about a choice of colour before opening the box?

1) replace all iron lock boxes with coloured ones according to accessory style eg. Fancy heavy etc

2) make the drop rate of rarer colours match those of the current rates for rarer styles eg. Divine prismatic etc

3) when opening a box it would contain a random accessory in the style of the box or in rare cases, an aura

4) shadow keys could be acquired in any box - although personally I would prefer them to just be vendor only (another discussion) - imagine opening a prismatic box and getting a key? Derp...

To implement would be fairly easy - stop the ability to sell lockboxes @ AH for a few days allowing current ones to sell. Then patch, convert all boxes in people's arsenals into random colours and change the prize wheel table.

This would hopefully achieve more diversity in the pricing of the boxes themselves and reduce the frustration of trying to aquire items to match the armour set you are wishing to accessorise...