I wanted to point out that there is no other slashing weapon in the game with base critical profile of 20/x2, so I think Vorpal Strikes should also make the unarmed base critical profile 19-20/x2 since it's changing the damage type to slashing.
This is on par with the PnP version of the game. In PnP there is a feat called Keen Strikes that is required in order to qualify for Vorpal Strikes. It makes your unarmed attacks deal slashing damage and gives you a base critical profile of 18-20/x2. I know 18-20 would be OP for the DDO version of the monk class but 19-20 would be just fine.
Many of you will say that there should be another feat for this reason and maybe make it a pre-req for Vorpal Strikes, but in PnP Vorpal Strikes does not change your damage type to slashing, Keen Strikes does. Apparently, the Devs merged these 2 feats into 1 and it's sad to see they left the best part of Keen Strikes out of the new implementation. I will say again: there is no other slashing weapon in this game with a base critical profile of 20/x2, so why does unarmed combat have to be any different?
For all other weapons there is a way to expand their critical profile, either with heroic enhancements or by using an epic destiny. Handwraps have been left out of this. Quarterstaves, a weapon with the same base critical profile as unarmed, can have a base critical profile of 19-20/x3 through either the Hensin Mystic or the Thief Acrobat trees, any weapon can have its critical threat range expanded by the Kensei tree.
This is something I've been thinking about for a very long time, but I chose to mention it now since the new end-game crafting system (Magma forge) has most of its melee oriented abilities proc On-Crit. I feel it's wrong for the monks out there to have no way of expanding their critical threat range in order to make these new cool weapons more effective, just like everyone else who's using a different kind of weapon.