The chests are the most interesting aspect of the game imo. After resetting, the chance to actually get one is too low. My suggestion is to increase the chance of getting a chest after defeating a boss, while decreasing the amount of good loot (epics & items) to balance it out. More chests = more fun, and you would actually start spending the common buffs more often instead of saving them (saving stuff is boring).

I'm not suggesting a decrease in chance to get good equipment, but a shift from where the rarity of chests is put into rarity of chests contens.

I'll try to clarify with an mathematically incorrect, and probably awful example.

How it is now (not real numbers as I don't know them).

Chest drop rate: 10% (1 chest on 10 bosses avarage)
Rare item content: 5% (1 in 20 chests contain a rare item)
=>1 rare item/200 bosses on avarage, or 0.5% chance per boss to get a rare item.

What I am suggesting:

Chest drop rate: 20% (1 chest on 5 bosses avarage)
Rare item content: 2,5% (1 in 40 chests contain a rare item)
=>1 rare item/200 bosses on avarage, or 0.5% chance per boss to get a rare item.

Of course it would need more balancing than this example is showing, but you get my idea I hope.

The point was not the numbers, but the shift of rarity.