There's a lot I can say about MD death, but here are some first thoughts.
In many ways I think death is currently more balanced than it's ever been. For the longest time there was a large divide between the MD bourgeoisie who had access to (someone with) a revival item to whom death mend nothing and the common folks to whom death might as well be a perma ban. Luckily some have offered to share their revival methods with the public and we now have the bees, so people quitting because they're killed isn't as much of a risk any more.
The biggest issue I currently see with killing is that people have no way to defend themselves. If someone uses a kill item, you're dead. Before making death any more severe I believe people need to have some way of defending themselves.
The simplest way I can think of is requiring the killer to defeat their victim in combat before allowing the kill to go through. If the victim wins the tool goes on cooldown without anything happening. (I believe this is how Eon's kill contracts used to work.) If you have no defense you always lose.
Furthermore you could give the victim an item that can be used to take revenge on the killer, at some significant cost.
There are a few things I can think off that would make killing more severe without being as abusable. The main one being a severe, long lasting but temporary side effect after being resurrected. For example:
For one week your stats are reduced by 100%, then for 1 week 95%, then 90% until after 20 weeks you're back to full strength.
Your regen timer is significantly reduced.
Maybe even make it so after being resurrected players lose stats when losing fights similar to someone being 1000 fights off balance.
Revive items are also too powerful. Having instant revives makes those who have access to them pretty much immune to death. Making it so those who get revived by normal revive items only get resurrected after a day or 2 would mean anyone who gets killed gets at least a little taste of death. This might make the bees option too powerful in comparison, in which case that method might have to be slowed down a little bit.
Finally a gold coin is to low a price. If you account for inflation one GC back when the price was introduced might be comparable to 5 GC now.