As far as I've noticed, there is a huge lack of melee weapon variety and actual usefulness as you get toward the higher levels. Speaking purely of DPS, nothing gets even close to the Balanced Slicing Sword, which has the potential to reach something like 1,400-1,500 DPS with a good craft and the right gear. That's enough to run a 1 man auto mission at high levels, with 0 ammo cost. Not a single melee weapon out there comes anywhere near that.
As for actual use during manual missions or the island (general PVP use) the only two melee weapons I see being used (and that I would use myself) are Balanced Slicing Swords and various different versions of the Warhammer (pulverizer, drivehammer, warhammer, etc.). Swords, obviously for the superb DPS they offer, and Hammers for the splash knockback, which is very useful for stopping large crowds of zombies.
I just think that there ought to be a MUCH larger variety of melee weaponry that would compare well to these weapons, since currently there really isn't anything out there better than these crafted melees. Some lootable melee weapons with DPS that can match or surpass the crafted swords' or ones with similar knockback effects to that of the hammers would be a welcome addition.
I know the fairly new tac blade gets a decent base DPS (better than that of the sword), but when you equip it for use in an actual mission (using a melee vest as gear), most average sword crafts will surpass even the highest quality tac blades. It seems that the melee combat boost that you can get on melee vests doesn't work as well on looted melees as it does on crafted ones, making looted melee weapons a far less useful tool than crafted melees for pretty much any PVP mission.
tl;dr Con should add more melee weapons that can compare to crafted ones.