As with the loss of experience, the loss of crystals is too much of a penalty for players to risk playing in places where they may die.

Some people say this will disrupt the crystal market, but I am asking: what market? All end game crystals are expensive and their creation and sale is unprofitable because the materials cost 90% of the crystal value.

But alright, there is a solution to the "crystal market problem": additional crystal enchantment. End game crystals can be enchanted to a higher lvl which will raise their stats and will be used for this ... crystals. Eg. crystal of elkarr gives up +12 accuracy and ignore all resistance 10%. So next lvl will give us eg. +15 accuracy and ignore all resistance 11%. 

And then we have crystal of elkarr +1 which for this requires 5 such crystals, and the next level, e.g. 10 such crystals. Additionally, other crystals can be used as substitutes in this system.